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National Cancer Institute Position on Medical Cannabis/Marijuana

The National Cancer Institute, formed in 1937, is part of the National Institutes for Health. NCI publishes the following overview on medical cannabis/marijuana on its website. This information is provided to demonstrate the NCI’s current official position on medical cannabis.

Link to NCI Medical Cannabis/Marijuana Position

Cannabis and Cannabinoids (PDQ®)–Health Professional Version

Overview

This cancer information summary provides an overview of the use of Cannabis and its components as a treatment for people with cancer-related symptoms caused by the disease itself or its treatment.

This summary contains the following key information:

  • Cannabis has been used for medicinal purposes for thousands of years.
  • By federal law, the possession of Cannabis is illegal in the United States, except within approved research settings; however, a growing number of states, territories, and the District of Columbia have enacted laws to legalize its medical use.
  • The U.S. Food and Drug Administration has not approved Cannabis as a treatment for cancer or any other medical condition.
  • Chemical components of Cannabis, called cannabinoids, activate specific receptors throughout the body to produce pharmacologic effects, particularly in the central nervous system and the immune system.
  • Commercially available cannabinoids, such as dronabinol and nabilone, are approved drugs for the treatment of cancer-related side effects.
  • Cannabinoids may have benefits in the treatment of cancer-related side effects.

Many of the medical and scientific terms used in this summary are hypertext linked (at first use in each section) to the NCI Dictionary of Cancer Terms, which is oriented toward nonexperts. When a linked term is clicked, a definition will appear in a separate window.

Reference citations in some PDQ cancer information summaries may include links to external websites that are operated by individuals or organizations for the purpose of marketing or advocating the use of specific treatments or products. These reference citations are included for informational purposes only. Their inclusion should not be viewed as an endorsement of the content of the websites, or of any treatment or product, by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board or the National Cancer Institute.

General Information

Cannabis , also known as marijuana, originated in Central Asia but is grown worldwide today. In the United States, it is a controlled substance and is classified as a Schedule I agent (a drug with a high potential for abuse, and no currently accepted medical use). The Cannabis plant produces a resin containing psychoactive compounds called cannabinoids, in addition to other compounds found in plants, such as terpenes and flavonoids. The highest concentration of cannabinoids is found in the female flowers of the plant.[1] Clinical trials conducted on medicinal Cannabis are limited. The U.S. Food and Drug Administration (FDA) has not approved the use of Cannabis as a treatment for any medical condition. To conduct clinical drug research with Cannabis in the United States, researchers must file an Investigational New Drug (IND) application with the FDA, obtain a Schedule I license from the U.S. Drug Enforcement Administration, and obtain approval from the National Institute on Drug Abuse.

The potential benefits of medicinal Cannabis for people living with cancer include antiemetic effects, appetite stimulation, pain relief, and improved sleep. Although few relevant surveys of practice patterns exist, it appears that physicians caring for cancer patients in the United States who recommend medicinal Cannabis do so predominantly for symptom management.[2] A growing number of pediatric patients are seeking symptom relief with Cannabis or cannabinoid treatment, although studies are limited.[3] The American Academy of Pediatrics has not endorsed Cannabis and cannabinoid use because of concerns about brain development.

Cannabinoids are a group of terpenophenolic compounds found in Cannabis species (e.g., Cannabis sativa L.). This summary will review the role of Cannabis and the cannabinoids in the treatment of people with cancer and disease-related or treatment-related side effects.

References
  1. Adams IB, Martin BR: Cannabis: pharmacology and toxicology in animals and humans. Addiction 91 (11): 1585-614, 1996. [PUBMED Abstract]
  2. Doblin RE, Kleiman MA: Marijuana as antiemetic medicine: a survey of oncologists’ experiences and attitudes. J Clin Oncol 9 (7): 1314-9, 1991. [PUBMED Abstract]
  3. Sallan SE, Cronin C, Zelen M, et al.: Antiemetics in patients receiving chemotherapy for cancer: a randomized comparison of delta-9-tetrahydrocannabinol and prochlorperazine. N Engl J Med 302 (3): 135-8, 1980. [PUBMED Abstract]

History

Cannabis use for medicinal purposes dates back at least 3,000 years.[15] It was introduced into Western medicine in 1839 by W.B. O’Shaughnessy, a surgeon who learned of its medicinal properties while working in India for the British East India Company. Its use was promoted for reported analgesic, sedative, anti-inflammatory, antispasmodic, and anticonvulsant effects.

In 1937, the U.S. Treasury Department introduced the Marihuana Tax Act. This Act imposed a levy of $1 per ounce for medicinal use of Cannabis and $100 per ounce for nonmedical use. Physicians in the United States were the principal opponents of the Act. The American Medical Association (AMA) opposed the Act because physicians were required to pay a special tax for prescribing Cannabis, use special order forms to procure it, and keep special records concerning its professional use. In addition, the AMA believed that objective evidence that Cannabis was harmful was lacking and that passage of the Act would impede further research into its medicinal worth.[6] In 1942, Cannabis was removed from the U.S. Pharmacopoeia because of persistent concerns about its potential to cause harm.[2,3]

In 1951, Congress passed the Boggs Act, which for the first time included Cannabis with narcotic drugs. In 1970, with the passage of the Controlled Substances Act, marijuana was classified by Congress as a Schedule I drug. Drugs in Schedule I are distinguished as having no currently accepted medicinal use in the United States. Other Schedule I substances include heroin, LSD, mescaline, and methaqualone.

Despite its designation as having no medicinal use, Cannabis was distributed by the U.S. government to patients on a case-by-case basis under the Compassionate Use Investigational New Drug program established in 1978. Distribution of Cannabis through this program was closed to new patients in 1992.[14] Although federal law prohibits the use of Cannabis, figure 1 below shows the states and territories that have legalized Cannabis use for medical purposes. Additional states have legalized only one ingredient in Cannabis, such as cannabidiol (CBD), and are not included in the map. Some medical marijuana laws are broader than others, and there is state-to-state variation as to the types of medical conditions for which treatment is allowed.

Enlarge
A map showing the U.S. states and territories that have approved the medical use of Cannabis.
Figure 1.
Cannabis map.

The main psychoactive constituent of Cannabis was identified as delta-9-tetrahydrocannabinol (THC). In 1986, an isomer of synthetic delta-9-THC in sesame oil was licensed and approved for the treatment of chemotherapy -associated nausea and vomiting under the generic name dronabinol. Clinical trials determined that dronabinol was as effective as or better than other antiemetic agents available at the time.[7] Dronabinol was also studied for its ability to stimulate weight gain in patients with AIDS in the late 1980s. Thus, the indications were expanded to include treatment of anorexia associated with human immunodeficiency virus infection in 1992. Clinical trial results showed no statistically significant weight gain, although patients reported an improvement in appetite.[8,9] Another important cannabinoid found in Cannabis is CBD.[10] This is a nonpsychoactive cannabinoid, which is an analog of THC.

In recent decades, the neurobiology of cannabinoids has been analyzed.[1114] The first cannabinoid receptor, CB1, was identified in the brain in 1988. A second cannabinoid receptor, CB2, was identified in 1993. The highest expression of CB2 receptors is located on B lymphocytes and natural killer cells, suggesting a possible role in immunity. Endogenous cannabinoids (endocannabinoids) have been identified and appear to have a role in pain modulation, control of movement, feeding behavior, mood, bone growth, inflammation, neuroprotection, and memory.[15]

Nabiximols (Sativex), a Cannabis extract with a 1:1 ratio of THC:CBD, is approved in Canada (under the Notice of Compliance with Conditions) for symptomatic relief of pain in advanced cancer and multiple sclerosis.[16] Canada, New Zealand, and some countries in Europe also approve nabiximols for spasticity of multiple sclerosis, a common symptom that may include muscle stiffness, reduced mobility, and pain, and for which existing therapy is unsatisfactory.

References
  1. Abel EL: Marihuana, The First Twelve Thousand Years. New York: Plenum Press, 1980. Also available online. Last accessed January 7, 2016.
  2. Joy JE, Watson SJ, Benson JA, eds.: Marijuana and Medicine: Assessing the Science Base. Washington, DC: National Academy Press, 1999. Also available online. Last accessed January 7, 2016.
  3. Mack A, Joy J: Marijuana As Medicine? The Science Beyond the Controversy. Washington, DC: National Academy Press, 2001. Also available online. Last accessed January 7, 2016.
  4. Booth M: Cannabis: A History. New York, NY: St Martin’s Press, 2003.
  5. Russo EB, Jiang HE, Li X, et al.: Phytochemical and genetic analyses of ancient cannabis from Central Asia. J Exp Bot 59 (15): 4171-82, 2008. [PUBMED Abstract]
  6. Schaffer Library of Drug Policy: The Marihuana Tax Act of 1937: Taxation of Marihuana. Washington, DC: House of Representatives, Committee on Ways and Means, 1937. Available online. Last accessed January 7, 2016.
  7. Sallan SE, Zinberg NE, Frei E 3rd: Antiemetic effect of delta-9-tetrahydrocannabinol in patients receiving cancer chemotherapy. N Engl J Med 293 (16): 795-7, 1975. [PUBMED Abstract]
  8. Gorter R, Seefried M, Volberding P: Dronabinol effects on weight in patients with HIV infection. AIDS 6 (1): 127, 1992. [PUBMED Abstract]
  9. Beal JE, Olson R, Laubenstein L, et al.: Dronabinol as a treatment for anorexia associated with weight loss in patients with AIDS. J Pain Symptom Manage 10 (2): 89-97, 1995. [PUBMED Abstract]
  10. Adams R, Hunt M, Clark JH: Structure of cannabidiol: a product isolated from the marihuana extract of Minnesota wild hemp. J Am Chem Soc 62 (1): 196-200, 1940. Also available online. Last accessed January 7, 2016.
  11. Devane WA, Dysarz FA 3rd, Johnson MR, et al.: Determination and characterization of a cannabinoid receptor in rat brain. Mol Pharmacol 34 (5): 605-13, 1988. [PUBMED Abstract]
  12. Devane WA, Hanus L, Breuer A, et al.: Isolation and structure of a brain constituent that binds to the cannabinoid receptor. Science 258 (5090): 1946-9, 1992. [PUBMED Abstract]
  13. Pertwee RG, Howlett AC, Abood ME, et al.: International Union of Basic and Clinical Pharmacology. LXXIX. Cannabinoid receptors and their ligands: beyond CB₁ and CB₂. Pharmacol Rev 62 (4): 588-631, 2010. [PUBMED Abstract]
  14. Felder CC, Glass M: Cannabinoid receptors and their endogenous agonists. Annu Rev Pharmacol Toxicol 38: 179-200, 1998. [PUBMED Abstract]
  15. Pacher P, Bátkai S, Kunos G: The endocannabinoid system as an emerging target of pharmacotherapy. Pharmacol Rev 58 (3): 389-462, 2006. [PUBMED Abstract]
  16. Howard P, Twycross R, Shuster J, et al.: Cannabinoids. J Pain Symptom Manage 46 (1): 142-9, 2013. [PUBMED Abstract]

Laboratory/Animal/Preclinical Studies

Cannabinoids are a group of 21-carbon–containing terpenophenolic compounds produced uniquely by Cannabis species (e.g., Cannabis sativa L.).[1,2] These plant-derived compounds may be referred to as phytocannabinoids. Although delta-9-tetrahydrocannabinol (THC) is the primary psychoactive ingredient, other known compounds with biologic activity are cannabinol, cannabidiol (CBD), cannabichromene, cannabigerol, tetrahydrocannabivarin, and delta-8-THC. CBD, in particular, is thought to have significant analgesic, anti-inflammatory, and anxiolytic activity without the psychoactive effect (high) of delta-9-THC.

Antitumor Effects

One study in mice and rats suggested that cannabinoids may have a protective effect against the development of certain types of tumors.[3] During this 2-year study, groups of mice and rats were given various doses of THC by gavage. A dose-related decrease in the incidence of hepatic adenoma tumors and hepatocellular carcinoma (HCC) was observed in the mice. Decreased incidences of benign tumors (polyps and adenomas) in other organs (mammary gland, uterus, pituitary, testis, and pancreas) were also noted in the rats. In another study, delta-9-THC, delta-8-THC, and cannabinol were found to inhibit the growth of Lewis lung adenocarcinoma cells in vitro and in vivo .[4] In addition, other tumors have been shown to be sensitive to cannabinoid-induced growth inhibition.[58]

Cannabinoids may cause antitumor effects by various mechanisms, including induction of cell death, inhibition of cell growth, and inhibition of tumor angiogenesis invasion and metastasis.[912] Two reviews summarize the molecular mechanisms of action of cannabinoids as antitumor agents.[13,14] Cannabinoids appear to kill tumor cells but do not affect their nontransformed counterparts and may even protect them from cell death. For example, these compounds have been shown to induce apoptosis in glioma cells in culture and induce regression of glioma tumors in mice and rats, while they protect normal glial cells of astroglial and oligodendroglial lineages from apoptosis mediated by the CB1 receptor.[9]

The effects of delta-9-THC and a synthetic agonist of the CB2 receptor were investigated in HCC.[15] Both agents reduced the viability of HCC cells in vitro and demonstrated antitumor effects in HCC subcutaneous xenografts in nude mice. The investigations documented that the anti-HCC effects are mediated by way of the CB2 receptor. Similar to findings in glioma cells, the cannabinoids were shown to trigger cell death through stimulation of an endoplasmic reticulum stress pathway that activates autophagy and promotes apoptosis. Other investigations have confirmed that CB1 and CB2 receptors may be potential targets in non-small cell lung carcinoma [16] and breast cancer.[17]

An in vitro study of the effect of CBD on programmed cell death in breast cancer cell lines found that CBD induced programmed cell death, independent of the CB1, CB2, or vanilloid receptors. CBD inhibited the survival of both estrogen receptor–positive and estrogen receptor–negative breast cancer cell lines, inducing apoptosis in a concentration-dependent manner while having little effect on nontumorigenic mammary cells.[18] Other studies have also shown the antitumor effect of cannabinoids (i.e., CBD and THC) in preclinical models of breast cancer.[19,20]

CBD has also been demonstrated to exert a chemopreventive effect in a mouse model of colon cancer.[21] In this experimental system, azoxymethane increased premalignant and malignant lesions in the mouse colon. Animals treated with azoxymethane and CBD concurrently were protected from developing premalignant and malignant lesions. In in vitro experiments involving colorectal cancer cell lines, the investigators found that CBD protected DNA from oxidative damage, increased endocannabinoid levels, and reduced cell proliferation. In a subsequent study, the investigators found that the antiproliferative effect of CBD was counteracted by selective CB1 but not CB2 receptor antagonists, suggesting an involvement of CB1 receptors.[22]

Another investigation into the antitumor effects of CBD examined the role of intercellular adhesion molecule-1 (ICAM-1).[12] ICAM-1 expression has been reported to be negatively correlated with cancer metastasis. In lung cancer cell lines, CBD upregulated ICAM-1, leading to decreased cancer cell invasiveness.

In an in vivo model using severe combined immunodeficient mice, subcutaneous tumors were generated by inoculating the animals with cells from human non-small cell lung carcinoma cell lines.[23] Tumor growth was inhibited by 60% in THC-treated mice compared with vehicle-treated control mice. Tumor specimens revealed that THC had antiangiogenic and antiproliferative effects. However, research with immunocompetent murine tumor models has demonstrated immunosuppression and enhanced tumor growth in mice treated with THC.[24,25]

In addition, both plant-derived and endogenous cannabinoids have been studied for anti-inflammatory effects. A mouse study demonstrated that endogenous cannabinoid system signaling is likely to provide intrinsic protection against colonic inflammation.[26] As a result, a hypothesis that phytocannabinoids and endocannabinoids may be useful in the risk reduction and treatment of colorectal cancer has been developed.[2730]

CBD may also enhance uptake of cytotoxic drugs into malignant cells. Activation of the transient receptor potential vanilloid type 2 (TRPV2) has been shown to inhibit proliferation of human glioblastoma multiforme cells and overcome resistance to the chemotherapy agent carmustine.[31] One study showed that coadministration of THC and CBD over single-agent usage had greater antiproliferative activity in an in vitro study with multiple human glioblastoma multiforme cell lines.[32] In an in vitro model, CBD increased TRPV2 activation and increased uptake of cytotoxic drugs, leading to apoptosis of glioma cells without affecting normal human astrocytes. This suggests that coadministration of CBD with cytotoxic agents may increase drug uptake and potentiate cell death in human glioma cells. Also, CBD together with THC may enhance the antitumor activity of classic chemotherapeutic drugs such as temozolomide in some mouse models of cancer.[13,33]

Antiemetic Effects

Preclinical research suggests that emetic circuitry is tonically controlled by endocannabinoids. The antiemetic action of cannabinoids is believed to be mediated via interaction with the 5-hydroxytryptamine 3 (5-HT3) receptor. CB1 receptors and 5-HT3 receptors are colocalized on gamma-aminobutyric acid (GABA)-ergic neurons, where they have opposite effects on GABA release.[34] There also may be direct inhibition of 5-HT3 gated ion currents through non–CB1 receptor pathways. CB1 receptor antagonists have been shown to elicit emesis in the least shrew that is reversed by cannabinoid agonists.[35] The involvement of CB1 receptor in emesis prevention has been shown by the ability of CB1 antagonists to reverse the effects of THC and other synthetic cannabinoid CB1 agonists in suppressing vomiting caused by cisplatin in the house musk shrew and lithium chloride in the least shrew. In the latter model, CBD was also shown to be efficacious.[36,37]

Appetite Stimulation

Many animal studies have previously demonstrated that delta-9-THC and other cannabinoids have a stimulatory effect on appetite and increase food intake. It is believed that the endogenous cannabinoid system may serve as a regulator of feeding behavior. The endogenous cannabinoid anandamide potently enhances appetite in mice.[38] Moreover, CB1 receptors in the hypothalamus may be involved in the motivational or reward aspects of eating.[39]

Analgesia

Understanding the mechanism of cannabinoid-induced analgesia has been increased through the study of cannabinoid receptors, endocannabinoids, and synthetic agonists and antagonists. Cannabinoids produce analgesia through supraspinal, spinal, and peripheral modes of action, acting on both ascending and descending pain pathways.[40]The CB1 receptor is found in both the central nervous system (CNS) and in peripheral nerve terminals. Similar to opioid receptors, increased levels of the CB1 receptor are found in regions of the brain that regulate nociceptive processing.[41] CB2 receptors, located predominantly in peripheral tissue, exist at very low levels in the CNS. With the development of receptor-specific antagonists, additional information about the roles of the receptors and endogenous cannabinoids in the modulation of pain has been obtained.[42,43]

Cannabinoids may also contribute to pain modulation through an anti-inflammatory mechanism; a CB2 effect with cannabinoids acting on mast cell receptors to attenuate the release of inflammatory agents, such as histamine and serotonin, and on keratinocytes to enhance the release of analgesic opioids has been described.[4446] One study reported that the efficacy of synthetic CB1- and CB2-receptor agonists were comparable with the efficacy of morphine in a murine model of tumor pain.[47]

Cannabinoids have been shown to prevent chemotherapy-induced neuropathy in animal models exposed to paclitaxel, vincristine, or cisplatin.[4850]

Anxiety and Sleep

The endocannabinoid system is believed to be centrally involved in the regulation of mood and the extinction of aversive memories. Animal studies have shown CBD to have anxiolytic properties. It was shown in rats that these anxiolytic properties are mediated through unknown mechanisms.[51] Anxiolytic effects of CBD have been shown in several animal models.[52,53]

The endocannabinoid system has also been shown to play a key role in the modulation of the sleep-waking cycle in rats.[54,55]

References
  1. Adams IB, Martin BR: Cannabis: pharmacology and toxicology in animals and humans. Addiction 91 (11): 1585-614, 1996. [PUBMED Abstract]
  2. Grotenhermen F, Russo E, eds.: Cannabis and Cannabinoids: Pharmacology, Toxicology, and Therapeutic Potential. Binghamton, NY: The Haworth Press, 2002.
  3. National Toxicology Program: NTP toxicology and carcinogenesis studies of 1-trans-delta(9)-tetrahydrocannabinol (CAS No. 1972-08-3) in F344 rats and B6C3F1 mice (gavage studies). Natl Toxicol Program Tech Rep Ser 446 (): 1-317, 1996. [PUBMED Abstract]
  4. Bifulco M, Laezza C, Pisanti S, et al.: Cannabinoids and cancer: pros and cons of an antitumour strategy. Br J Pharmacol 148 (2): 123-35, 2006. [PUBMED Abstract]
  5. Sánchez C, de Ceballos ML, Gomez del Pulgar T, et al.: Inhibition of glioma growth in vivo by selective activation of the CB(2) cannabinoid receptor. Cancer Res 61 (15): 5784-9, 2001. [PUBMED Abstract]
  6. McKallip RJ, Lombard C, Fisher M, et al.: Targeting CB2 cannabinoid receptors as a novel therapy to treat malignant lymphoblastic disease. Blood 100 (2): 627-34, 2002. [PUBMED Abstract]
  7. Casanova ML, Blázquez C, Martínez-Palacio J, et al.: Inhibition of skin tumor growth and angiogenesis in vivo by activation of cannabinoid receptors. J Clin Invest 111 (1): 43-50, 2003. [PUBMED Abstract]
  8. Blázquez C, González-Feria L, Alvarez L, et al.: Cannabinoids inhibit the vascular endothelial growth factor pathway in gliomas. Cancer Res 64 (16): 5617-23, 2004. [PUBMED Abstract]
  9. Guzmán M: Cannabinoids: potential anticancer agents. Nat Rev Cancer 3 (10): 745-55, 2003. [PUBMED Abstract]
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  12. Ramer R, Bublitz K, Freimuth N, et al.: Cannabidiol inhibits lung cancer cell invasion and metastasis via intercellular adhesion molecule-1. FASEB J 26 (4): 1535-48, 2012. [PUBMED Abstract]
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  20. McAllister SD, Murase R, Christian RT, et al.: Pathways mediating the effects of cannabidiol on the reduction of breast cancer cell proliferation, invasion, and metastasis. Breast Cancer Res Treat 129 (1): 37-47, 2011. [PUBMED Abstract]
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  27. Patsos HA, Hicks DJ, Greenhough A, et al.: Cannabinoids and cancer: potential for colorectal cancer therapy. Biochem Soc Trans 33 (Pt 4): 712-4, 2005. [PUBMED Abstract]
  28. Liu WM, Fowler DW, Dalgleish AG: Cannabis-derived substances in cancer therapy–an emerging anti-inflammatory role for the cannabinoids. Curr Clin Pharmacol 5 (4): 281-7, 2010. [PUBMED Abstract]
  29. Malfitano AM, Ciaglia E, Gangemi G, et al.: Update on the endocannabinoid system as an anticancer target. Expert Opin Ther Targets 15 (3): 297-308, 2011. [PUBMED Abstract]
  30. Sarfaraz S, Adhami VM, Syed DN, et al.: Cannabinoids for cancer treatment: progress and promise. Cancer Res 68 (2): 339-42, 2008. [PUBMED Abstract]
  31. Nabissi M, Morelli MB, Santoni M, et al.: Triggering of the TRPV2 channel by cannabidiol sensitizes glioblastoma cells to cytotoxic chemotherapeutic agents. Carcinogenesis 34 (1): 48-57, 2013. [PUBMED Abstract]
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  34. Pacher P, Bátkai S, Kunos G: The endocannabinoid system as an emerging target of pharmacotherapy. Pharmacol Rev 58 (3): 389-462, 2006. [PUBMED Abstract]
  35. Darmani NA: Delta(9)-tetrahydrocannabinol and synthetic cannabinoids prevent emesis produced by the cannabinoid CB(1) receptor antagonist/inverse agonist SR 141716A. Neuropsychopharmacology 24 (2): 198-203, 2001. [PUBMED Abstract]
  36. Darmani NA: Delta-9-tetrahydrocannabinol differentially suppresses cisplatin-induced emesis and indices of motor function via cannabinoid CB(1) receptors in the least shrew. Pharmacol Biochem Behav 69 (1-2): 239-49, 2001 May-Jun. [PUBMED Abstract]
  37. Parker LA, Kwiatkowska M, Burton P, et al.: Effect of cannabinoids on lithium-induced vomiting in the Suncus murinus (house musk shrew). Psychopharmacology (Berl) 171 (2): 156-61, 2004. [PUBMED Abstract]
  38. Mechoulam R, Berry EM, Avraham Y, et al.: Endocannabinoids, feeding and suckling–from our perspective. Int J Obes (Lond) 30 (Suppl 1): S24-8, 2006. [PUBMED Abstract]
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  45. Ibrahim MM, Porreca F, Lai J, et al.: CB2 cannabinoid receptor activation produces antinociception by stimulating peripheral release of endogenous opioids. Proc Natl Acad Sci U S A 102 (8): 3093-8, 2005. [PUBMED Abstract]
  46. Richardson JD, Kilo S, Hargreaves KM: Cannabinoids reduce hyperalgesia and inflammation via interaction with peripheral CB1 receptors. Pain 75 (1): 111-9, 1998. [PUBMED Abstract]
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  48. Ward SJ, McAllister SD, Kawamura R, et al.: Cannabidiol inhibits paclitaxel-induced neuropathic pain through 5-HT(1A) receptors without diminishing nervous system function or chemotherapy efficacy. Br J Pharmacol 171 (3): 636-45, 2014. [PUBMED Abstract]
  49. Rahn EJ, Makriyannis A, Hohmann AG: Activation of cannabinoid CB1 and CB2 receptors suppresses neuropathic nociception evoked by the chemotherapeutic agent vincristine in rats. Br J Pharmacol 152 (5): 765-77, 2007. [PUBMED Abstract]
  50. Khasabova IA, Khasabov S, Paz J, et al.: Cannabinoid type-1 receptor reduces pain and neurotoxicity produced by chemotherapy. J Neurosci 32 (20): 7091-101, 2012. [PUBMED Abstract]
  51. Campos AC, Guimarães FS: Involvement of 5HT1A receptors in the anxiolytic-like effects of cannabidiol injected into the dorsolateral periaqueductal gray of rats. Psychopharmacology (Berl) 199 (2): 223-30, 2008. [PUBMED Abstract]
  52. Crippa JA, Zuardi AW, Hallak JE: [Therapeutical use of the cannabinoids in psychiatry]. Rev Bras Psiquiatr 32 (Suppl 1): S56-66, 2010. [PUBMED Abstract]
  53. Guimarães FS, Chiaretti TM, Graeff FG, et al.: Antianxiety effect of cannabidiol in the elevated plus-maze. Psychopharmacology (Berl) 100 (4): 558-9, 1990. [PUBMED Abstract]
  54. Méndez-Díaz M, Caynas-Rojas S, Arteaga Santacruz V, et al.: Entopeduncular nucleus endocannabinoid system modulates sleep-waking cycle and mood in rats. Pharmacol Biochem Behav 107: 29-35, 2013. [PUBMED Abstract]
  55. Pava MJ, den Hartog CR, Blanco-Centurion C, et al.: Endocannabinoid modulation of cortical up-states and NREM sleep. PLoS One 9 (2): e88672, 2014. [PUBMED Abstract]

Human/Clinical Studies

Cannabis Pharmacology

When oral Cannabis is ingested, there is a low (6%–20%) and variable oral bioavailability.[1,2] Peak plasma concentrations of delta-9-tetrahydrocannabinol (THC) occur after 1 to 6 hours and remain elevated with a terminal half-life of 20 to 30 hours. Taken by mouth, delta-9-THC is initially metabolized in the liver to 11-OH-THC, a potent psychoactive metabolite. Inhaled cannabinoids are rapidly absorbed into the bloodstream with a peak concentration in 2 to 10 minutes, declining rapidly for a period of 30 minutes and with less generation of the psychoactive 11-OH metabolite.

Cannabinoids are known to interact with the hepatic cytochrome P450 enzyme system.[3,4] In one study, 24 cancer patients were treated with intravenous irinotecan (600 mg, n = 12) or docetaxel (180 mg, n = 12), followed 3 weeks later by the same drugs concomitant with medicinal Cannabis taken in the form of an herbal tea for 15 consecutive days, starting 12 days before the second treatment.[4] The administration of Cannabis did not significantly influence exposure to and clearance of irinotecan or docetaxel, although the herbal tea route of administration may not reproduce the effects of inhalation or oral ingestion of fat-soluble cannabinoids.

Cancer Risk

A number of studies have yielded conflicting evidence regarding the risks of various cancers associated with Cannabis use.

A pooled analysis of three case-cohort studies of men in northwestern Africa (430 cases and 778 controls) showed a significantly increased risk of lung cancer among tobacco smokers who also inhaled Cannabis.[5]

A large, retrospective cohort study of 64,855 men aged 15 to 49 years from the United States found that Cannabis use was not associated with tobacco-related cancers and a number of other common malignancies. However, the study did find that, among nonsmokers of tobacco, ever having used Cannabis was associated with an increased risk of prostate cancer.[6]

A population-based case-control study of 611 lung cancer patients revealed that chronic low Cannabis exposure was not associated with an increased risk of lung cancer or other upper aerodigestive tract cancers and found no positive associations with any cancer type (oral, pharyngeal, laryngeal, lung, or esophagus) when adjusting for several confounders, including cigarette smoking.[7]

A systematic review assessing 19 studies that evaluated premalignant or malignant lung lesions in persons 18 years or older who inhaled Cannabis concluded that observational studies failed to demonstrate statistically significant associations between Cannabis inhalation and lung cancer after adjusting for tobacco use.[8]

Epidemiologic studies examining one association of Cannabis use with head and neck squamous cell carcinomas have also been inconsistent in their findings. A pooled analysis of nine case-control studies from the U.S./Latin American International Head and Neck Cancer Epidemiology (INHANCE) Consortium included information from 1,921 oropharyngeal cases, 356 tongue cases, and 7,639 controls. Compared with those who never smoked Cannabis, Cannabis smokers had an elevated risk of oropharyngeal cancers and a reduced risk of tongue cancer. These study results both reflect the inconsistent effects of cannabinoids on cancer incidence noted in previous studies and suggest that more work needs to be done to understand the potential role of human papillomavirus infection.[9]

With a hypothesis that chronic marijuana use produces adverse effects on the human endocrine and reproductive systems, the association between Cannabis use and incidence of testicular germ cell tumors (TGCTs) has been examined.[1012] Three population-based case-control studies reported an association between Cannabis use and elevated risk of TGCTs, especially nonseminoma or mixed-histology tumors.[1012] However, the sample sizes in these studies were inadequate to address Cannabis dose by addressing associations with respect to recency, frequency, and duration of use. These early reports of Cannabis use and TGCTs established the need for larger, well-powered, prospective studies, especially studies evaluating the role of endocannabinoid signaling and cannabinoid receptors in TGCTs.

An analysis of 84,170 participants in the California Men’s Health Study was performed to investigate the association between Cannabis use and the incidence of bladder cancer. During 16 years of follow-up, 89 Cannabis users (0.3%) developed bladder cancer compared with 190 (0.4%) of the men who did not report Cannabis use (P < .001). After adjusting for age, race, ethnicity, and body mass index, Cannabis use was associated with a 45% reduction in bladder cancer incidence (hazard ratio, 0.55; 95% confidence interval, 0.33–1.00).[13]

A comprehensive Health Canada monograph on marijuana concluded that while there are many cellular and molecular studies that provide strong evidence that inhaled marijuana is carcinogenic, the epidemiologic evidence of a link between marijuana use and cancer is still inconclusive.[14]

Cancer Treatment

Clinical data in pediatric use is limited to a few case reports.[15,16] No clinical trials of Cannabis as a treatment for cancer in humans were identified in a PubMed search; however, a single, small study of intratumoral injection of delta-9-THC in patients with recurrent glioblastoma multiforme reported potential antitumoral activity.[17,18] In a trial that is now closed, controlled human studies investigated oral cannabidiol (CBD) as a single agent for solid tumors, using a 1:1 ratio of THC:CBD in a Cannabis-based medicinal extract oromucosal spray in conjunction with temozolomide in treating patients with recurrent glioblastoma multiforme (GWCA1208 Part A [NCT01812603]) and CBD as a treatment for acute graft-versus-host disease in patients who have undergone allogeneic hematopoietic stem cell transplantation (NCT01596075).

Antiemetic Effect

Cannabinoids

Despite advances in pharmacologic and nonpharmacologic management, nausea and vomiting (N/V) remain distressing side effects for cancer patients and their families. Dronabinol, a synthetically produced delta-9-THC, was approved in the United States in 1986 as an antiemetic to be used in cancer chemotherapy. Nabilone, a synthetic derivative of delta-9-THC, was first approved in Canada in 1982 and is now also available in the United States.[19] Both dronabinol and nabilone have been approved by the U.S. Food and Drug Administration for the treatment of N/V associated with cancer chemotherapy in patients who have failed to respond to conventional antiemetic therapy. Numerous clinical trials and meta-analyses have shown that dronabinol and nabilone are effective in the treatment of N/V induced by chemotherapy.[2023] The National Comprehensive Cancer Network Guidelines recommend cannabinoids as breakthrough treatment for chemotherapy-related N/V.

One systematic review studied 30 randomized comparisons of delta-9-THC preparations with placebo or other antiemetics from which data on efficacy and harm were available.[24] Oral nabilone, oral dronabinol, and intramuscular levonantradol (a synthetic analog of dronabinol) were tested. Inhaled Cannabis trials were not included. Among all 1,366 patients included in the review, cannabinoids were found to be more effective than the conventional antiemetics prochlorperazine, metoclopramide, chlorpromazine, thiethylperazine, haloperidol, domperidone, and alizapride. Cannabinoids, however, were not more effective for patients receiving very low or very high emetogenic chemotherapy. Side effects included a feeling of being high, euphoria, sedation or drowsiness, dizziness, dysphoria or depression, hallucinations, paranoia, and hypotension.[24]

Another analysis of 15 controlled studies compared nabilone with placebo or available antiemetic drugs.[25] Among 600 cancer patients, nabilone was found to be superior to prochlorperazine, domperidone, and alizapride, with nabilone favored for continuous use.

(Refer to the Cannabis section in the PDQ summary on Nausea and Vomiting for more information.)

Cannabis

Ten trials have evaluated the efficacy of inhaled Cannabis in chemotherapy-induced N/V.[2629] In two of the studies, inhaled Cannabis was made available only after dronabinol failure. In the first trial, no antiemetic effect was achieved with marijuana in patients receiving cyclophosphamide or doxorubicin,[26] but in the second trial, a statistically significant superior antiemetic effect of inhaled Cannabis versus placebo was found among patients receiving high-dose methotrexate.[27] The third trial was a randomized, double-blind, placebo-controlled, cross-over trial involving 20 adults in which both inhaled marijuana and oral THC were evaluated. One-quarter of the patients reported a favorable antiemetic response to the cannabinoid therapies. This latter study was reported in abstract form in 1984. A full report, detailing the methods and outcomes apparently has not been published, which limits a thorough interpretation of the significance of these findings.[28]

Newer antiemetics (e.g., 5-hydroxytryptamine 3 [5-HT3] receptor antagonists) have not been directly compared with Cannabis or cannabinoids in cancer patients. However, the Cannabis-extract oromucosal spray, nabiximols, formulated with 1:1 THC:CBD was shown in a small pilot randomized, placebo-controlled, double-blinded clinical trial in Spain to treat chemotherapy-related N/V.[30][Level of evidence: 1iC]

Appetite Stimulation

Anorexia, early satiety, weight loss, and cachexia are problems experienced by cancer patients. Such patients are faced not only with the disfigurement associated with wasting but also with an inability to engage in the social interaction of meals.

Cannabinoids

Three controlled trials demonstrated that oral THC has variable effects on appetite stimulation and weight loss in patients with advanced malignancies and human immunodeficiency virus (HIV) infection.[25] One study evaluated the efficacy of dronabinol alone or with megestrol acetate compared with that of megestrol acetate alone for managing cancer-associated anorexia.[31] In this randomized, double-blind study of 469 adults with advanced cancer and weight loss, patients received 2.5 mg of oral THC twice daily, 800 mg of oral megestrol daily, or both. Appetite increased by 75% in the megestrol group and weight increased by 11%, compared with a 49% increase in appetite and a 3% increase in weight in the oral THC group after 8 to 11 weeks of treatment. These two differences were statistically significant. Furthermore, the combined therapy did not offer additional benefits beyond those provided by megestrol acetate alone. The authors concluded that dronabinol did little to promote appetite or weight gain in advanced cancer patients compared with megestrol acetate. However, a smaller, placebo-controlled trial of dronabinol in cancer patients demonstrated improved and enhanced chemosensory perception in the cannabinoid group—food tasted better, appetite increased, and the proportion of calories consumed as protein was greater than in the placebo recipients.[32]

In a randomized clinical trial, researchers compared the safety and effectiveness of orally administered Cannabis extract (2.5 mg THC and 1 mg CBD), THC (2.5 mg), or placebo for the treatment of cancer-related anorexia-cachexia in 243 patients with advanced cancer who received treatment twice daily for 6 weeks. Results demonstrated that although these agents were well tolerated by these patients, no differences were observed in patient appetite or quality of life among the three groups at this dose level and duration of intervention.[33]

Another clinical trial that involved 139 patients with HIV or AIDS and weight loss found that, compared with placebo, oral dronabinol was associated with a statistically significant increase in appetite after 4 to 6 weeks of treatment. Patients receiving dronabinol tended to have weight stabilization, whereas patients receiving placebo continued to lose weight.[34]

Cannabis

In trials conducted in the 1980s that involved healthy control subjects, inhaling Cannabis led to an increase in caloric intake, mainly in the form of between-meal snacks, with increased intakes of fatty and sweet foods.[35,36]

No published studies have explored the effect of inhaled Cannabis on appetite in cancer patients.

Analgesia

Cannabinoids

Pain management improves a patient’s quality of life throughout all stages of cancer. Through the study of cannabinoid receptors, endocannabinoids, and synthetic agonists and antagonists, the mechanisms of cannabinoid-induced analgesia have been analyzed.[37][Level of evidence:1iC] The CB1 receptor is found in the central nervous system (CNS) and in peripheral nerve terminals.[38] CB2 receptors are located mainly in peripheral tissue and are expressed in only low amounts in the CNS. Whereas only CB1 agonists exert analgesic activity in the CNS, both CB1 and CB2 agonists have analgesic activity in peripheral tissue.[39,40]

Cancer pain results from inflammation, invasion of bone or other pain-sensitive structures, or nerve injury. When cancer pain is severe and persistent, it is often resistant to treatment with opioids.

Two studies examined the effects of oral delta-9-THC on cancer pain. The first, a double-blind placebo-controlled study involving ten patients, measured both pain intensity and pain relief.[41] It was reported that 15 mg and 20 mg doses of the cannabinoid delta-9-THC were associated with substantial analgesic effects, with antiemetic effects and appetite stimulation.

In a follow-up, single-dose study involving 36 patients, it was reported that 10 mg doses of delta-9-THC produced analgesic effects during a 7-hour observation period that were comparable to 60 mg doses of codeine, and 20 mg doses of delta-9-THC induced effects equivalent to 120 mg doses of codeine.[42] Higher doses of THC were found to be more sedative than codeine.

Another study examined the effects of a plant extract with controlled cannabinoid content in an oromucosal spray. In a multicenter, double-blind, placebo-controlled study, the THC:CBD nabiximols extract and THC extract alone were compared in the analgesic management of patients with advanced cancer and with moderate-to-severe cancer-related pain. Patients were assigned to one of three treatment groups: THC:CBD extract, THC extract, or placebo. The researchers concluded that the THC:CBD extract was efficacious for pain relief in advanced cancer patients whose pain was not fully relieved by strong opioids.[43] In a randomized, placebo-controlled, graded-dose trial, opioid-treated cancer patients with poorly controlled chronic pain demonstrated significantly better control of pain and sleep disruption with THC:CBD oromucosal spray at lower doses (1–4 and 6–10 sprays/day), compared with placebo. Adverse events were dose related, with only the high-dose group (11–16 sprays/day) comparing unfavorably with the placebo arm. These studies provide promising evidence of an “adjuvant analgesic” effect of THC:CBD in this opioid-refractory patient population and may provide an opportunity to address this significant clinical challenge.[44] An open-label extension study of 43 patients who had participated in the randomized trial found that some patients continued to obtain relief of their cancer-related pain with long-term use of the THC:CBD oromucosal spray without increasing their dose of the spray or the dose of their other analgesics.[45]

A randomized, placebo-controlled, crossover pilot study of nabiximols in 16 patients with chemotherapy-induced neuropathic pain showed no significant difference between the treatment and placebo groups. A responder analysis, however, demonstrated that five patients reported a reduction in their pain of at least 2 points on an 11-point scale, suggesting that a larger follow-up study may be warranted.[46]

An observational study assessed the effectiveness of nabilone in advanced cancer patients who were experiencing pain and other symptoms (anorexia, depression, and anxiety). The researchers reported that patients who used nabilone experienced improved management of pain, nausea, anxiety, and distress when compared with untreated patients. Nabilone was also associated with a decreased use of opioids, nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, gabapentin, dexamethasone, metoclopramide, and ondansetron.[47]

Cannabis

Animal studies have suggested a synergistic analgesic effect when cannabinoids are combined with opioids. The results from one pharmacokinetic interaction study have been reported. In this study, 21 patients with chronic pain were administered vaporized Cannabis along with sustained-release morphine or oxycodone for 5 days.[48] The patients who received vaporized Cannabis and sustained-release morphine had a statistically significant decrease in their mean pain score over the 5-day period; those who received vaporized Cannabis and oxycodone did not. These findings should be verified by further studies before recommendations favoring such an approach are warranted in general clinical practice.

Neuropathic pain is a symptom cancer patients may experience, especially if treated with platinum-based chemotherapy or taxanes. Two randomized controlled trials of inhaled Cannabis in patients with peripheral neuropathy or neuropathic pain of various etiologies found that pain was reduced in patients who received inhaled Cannabis, compared with those who received placebo.[49,50] Two additional trials of inhaled Cannabis have also demonstrated the benefit of Cannabis over placebo in HIV-associated neuropathic pain.[51,52]

Anxiety and Sleep

Cannabinoids

In a small pilot study of analgesia involving ten patients with cancer pain, secondary measures showed that 15 mg and 20 mg doses of the cannabinoid delta-9-THC were associated with anxiolytic effects.[41][Level of evidence: 1iC]

A small placebo-controlled study of dronabinol in cancer patients with altered chemosensory perception also noted increased quality of sleep and relaxation in THC-treated patients.[32][Level of evidence: 1iC]

Cannabis

Patients often experience mood elevation after exposure to Cannabis, depending on their previous experience. In a five-patient case series of inhaled Cannabis that examined analgesic effects in chronic pain, it was reported that patients who self-administered Cannabis had improved mood, improved sense of well-being, and less anxiety.[53]

Another common effect of Cannabis is sleepiness. A small placebo-controlled study of dronabinol in cancer patients with altered chemosensory perception also noted increased quality of sleep and relaxation in THC-treated patients.[32]

Clinical Studies of Cannabis and Cannabinoids

Table 1. Clinical Studies of
Cannabis
a
Reference Citation Type of Study Condition Treated No. of Patients: Enrolled; Treated; Controlb Strongest Benefit Reportedc Concurrent Therapy Used (Yes/No/ Unknown)d Level of Evidence Scoree
CINV = chemotherapy-induced nausea and vomiting; HIV = human immunodeficiency virus; RCT = randomized controlled trial; N/V = nausea and vomiting.
aRefer to text and the NCI Dictionary of Cancer Terms for additional information and definition of terms.
bNumber of patients treated plus number of patient controls may not equal number of patients enrolled; number of patients enrolled equals number of patients initially recruited/considered by the researchers who conducted a study; number of patients treated equals number of enrolled patients who were given the treatment being studied AND for whom results were reported.
cStrongest evidence reported that the treatment under study has activity or otherwise improves the well-being of cancer patients.
dConcurrent therapy for symptoms treated (not cancer).
eFor information about levels of evidence analysis and an explanation of the level of evidence scores, refer to Levels of Evidence for Human Studies of Integrative, Alternative, and Complementary Therapies.
[26] RCT CINV 8; 8; None None Unknown 1iC
[27] RCT CINV 15; 15; None Decreased N/V Unknown 1iiC
[30] Pilot RCT CINV 16; 7; 9 Decreased/delayed N/V 5-HT3 receptor antagonists 1iC
Table 2. Clinical Studies of Cannabinoids
a
Reference Citation Type of Study Condition Treated No. of Patients: Enrolled; Treated; Controlb Strongest Benefit Reportedc Concurrent Therapy Used (Yes/No/ Unknown)d Level of Evidence Scoree
No. = number; QoL = quality of life; RCT = randomized controlled trial; THC = delta-9-tetrahydrocannabinol.
aRefer to text and the NCI Dictionary of Cancer Terms for additional information and definition of terms.
bNumber of patients treated plus number of patient controls may not equal number of patients enrolled; number of patients enrolled equals number of patients initially recruited/considered by the researchers who conducted a study; number of patients treated equals number of enrolled patients who were given the treatment being studied AND for whom results were reported.
cStrongest evidence reported that the treatment under study has activity or otherwise improves the well-being of cancer patients.
dConcurrent therapy for symptoms treated (not cancer).
eFor information about levels of evidence analysis and an explanation of the level of evidence scores, refer to Levels of Evidence for Human Studies of Integrative, Alternative, and Complementary Therapies.
[31] RCT Cancer-associated anorexia 469; dronabinol 152, megestrol acetate 159, or both 158; none Megestrol acetate provided superior anorexia palliation among advanced cancer patients compared with dronabinol alone Unknown 1iC
[32] Pilot RCT Appetite 21; 11; 10 THC, compared with placebo, improved and enhanced chemosensory perception Unknown 1iC
[33] RCT Cancer-related anorexia-cachexia syndrome 243; Cannabis extract 95, THC 100; 48 No differences in patients’ appetite or QoL were found Unknown 1iC
[34] RCT Appetite 139; 72; 67 Increase in appetite Unknown 1iC
[37] Survey of RCTs Pain Decreased pain Unknown 1iC
[41] RCT Pain 10; none; none Pain relief Unknown 1iC
[47] Observational study Pain 112; 47; 65 Decreased pain

Current Clinical Trials

Check the list of NCI-supported cancer clinical trials for cancer CAM clinical trials on dronabinol, marijuana, nabiximols, nabilone and cannabidiol that are actively enrolling patients.

General information about clinical trials is also available from the NCI website.

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  43. Johnson JR, Burnell-Nugent M, Lossignol D, et al.: Multicenter, double-blind, randomized, placebo-controlled, parallel-group study of the efficacy, safety, and tolerability of THC:CBD extract and THC extract in patients with intractable cancer-related pain. J Pain Symptom Manage 39 (2): 167-79, 2010. [PUBMED Abstract]
  44. Portenoy RK, Ganae-Motan ED, Allende S, et al.: Nabiximols for opioid-treated cancer patients with poorly-controlled chronic pain: a randomized, placebo-controlled, graded-dose trial. J Pain 13 (5): 438-49, 2012. [PUBMED Abstract]
  45. Johnson JR, Lossignol D, Burnell-Nugent M, et al.: An open-label extension study to investigate the long-term safety and tolerability of THC/CBD oromucosal spray and oromucosal THC spray in patients with terminal cancer-related pain refractory to strong opioid analgesics. J Pain Symptom Manage 46 (2): 207-18, 2013. [PUBMED Abstract]
  46. Lynch ME, Cesar-Rittenberg P, Hohmann AG: A double-blind, placebo-controlled, crossover pilot trial with extension using an oral mucosal cannabinoid extract for treatment of chemotherapy-induced neuropathic pain. J Pain Symptom Manage 47 (1): 166-73, 2014. [PUBMED Abstract]
  47. Maida V, Ennis M, Irani S, et al.: Adjunctive nabilone in cancer pain and symptom management: a prospective observational study using propensity scoring. J Support Oncol 6 (3): 119-24, 2008. [PUBMED Abstract]
  48. Abrams DI, Couey P, Shade SB, et al.: Cannabinoid-opioid interaction in chronic pain. Clin Pharmacol Ther 90 (6): 844-51, 2011. [PUBMED Abstract]
  49. Wilsey B, Marcotte T, Deutsch R, et al.: Low-dose vaporized cannabis significantly improves neuropathic pain. J Pain 14 (2): 136-48, 2013. [PUBMED Abstract]
  50. Wilsey B, Marcotte T, Tsodikov A, et al.: A randomized, placebo-controlled, crossover trial of cannabis cigarettes in neuropathic pain. J Pain 9 (6): 506-21, 2008. [PUBMED Abstract]
  51. Abrams DI, Jay CA, Shade SB, et al.: Cannabis in painful HIV-associated sensory neuropathy: a randomized placebo-controlled trial. Neurology 68 (7): 515-21, 2007. [PUBMED Abstract]
  52. Ellis RJ, Toperoff W, Vaida F, et al.: Smoked medicinal cannabis for neuropathic pain in HIV: a randomized, crossover clinical trial. Neuropsychopharmacology 34 (3): 672-80, 2009. [PUBMED Abstract]
  53. Noyes R Jr, Baram DA: Cannabis analgesia. Compr Psychiatry 15 (6): 531-5, 1974 Nov-Dec. [PUBMED Abstract]

Adverse Effects

Cannabis and Cannabinoids

Because cannabinoid receptors, unlike opioid receptors, are not located in the brainstem areas controlling respiration, lethal overdoses from Cannabis and cannabinoids do not occur.[14] However, cannabinoid receptors are present in other tissues throughout the body, not just in the central nervous system, and adverse effects include tachycardia, hypotension, conjunctival injection, bronchodilation, muscle relaxation, and decreased gastrointestinal motility.

Although cannabinoids are considered by some to be addictive drugs, their addictive potential is considerably lower than that of other prescribed agents or substances of abuse.[2,4] The brain develops a tolerance to cannabinoids.

Withdrawal symptoms such as irritability, insomnia with sleep electroencephalogram disturbance, restlessness, hot flashes, and, rarely, nausea and cramping have been observed. However, these symptoms appear to be mild compared with withdrawal symptoms associated with opiates or benzodiazepines, and the symptoms usually dissipate after a few days.

Unlike other commonly used drugs, cannabinoids are stored in adipose tissue and excreted at a low rate (half-life 1–3 days), so even abrupt cessation of cannabinoid intake is not associated with rapid declines in plasma concentrations that would precipitate severe or abrupt withdrawal symptoms or drug cravings.

Since Cannabis smoke contains many of the same components as tobacco smoke, there are valid concerns about the adverse pulmonary effects of inhaled Cannabis. A longitudinal study in a noncancer population evaluated repeated measurements of pulmonary function over 20 years in 5,115 men and women whose smoking histories were known.[5] While tobacco exposure was associated with decreased pulmonary function, the investigators concluded that occasional and low-cumulative Cannabis use was not associated with adverse effects on pulmonary function (forced expiratory volume in the first second of expiration [FEV1] and forced vital capacity [FVC]).

References
  1. Adams IB, Martin BR: Cannabis: pharmacology and toxicology in animals and humans. Addiction 91 (11): 1585-614, 1996. [PUBMED Abstract]
  2. Grotenhermen F, Russo E, eds.: Cannabis and Cannabinoids: Pharmacology, Toxicology, and Therapeutic Potential. Binghamton, NY: The Haworth Press, 2002.
  3. Sutton IR, Daeninck P: Cannabinoids in the management of intractable chemotherapy-induced nausea and vomiting and cancer-related pain. J Support Oncol 4 (10): 531-5, 2006 Nov-Dec. [PUBMED Abstract]
  4. Guzmán M: Cannabinoids: potential anticancer agents. Nat Rev Cancer 3 (10): 745-55, 2003. [PUBMED Abstract]
  5. Pletcher MJ, Vittinghoff E, Kalhan R, et al.: Association between marijuana exposure and pulmonary function over 20 years. JAMA 307 (2): 173-81, 2012. [PUBMED Abstract]

Summary of the Evidence for Cannabis and Cannabinoids

To assist readers in evaluating the results of human studies of integrative, alternative, and complementary therapies for people with cancer, the strength of the evidence (i.e., the levels of evidence) associated with each type of treatment is provided whenever possible. To qualify for a level of evidence analysis, a study must:

Separate levels of evidence scores are assigned to qualifying human studies on the basis of statistical strength of the study design and scientific strength of the treatment outcomes (i.e., endpoints) measured. The resulting two scores are then combined to produce an overall score. An overall level of evidence score cannot be assigned to cannabinoids because there has been insufficient clinical research to date. For an explanation of possible scores and additional information about levels of evidence analysis of CAM treatments for people with cancer, refer to Levels of Evidence for Human Studies of Integrative, Alternative, and Complementary Therapies.

Cannabinoids

Cannabis

  • There have been ten clinical trials on the use of inhaled Cannabis in cancer patients that can be divided into two groups. In one group, four small studies assessed antiemetic activity but each explored a different patient population and chemotherapy regimen. One study demonstrated no effect, the second study showed a positive effect versus placebo, the report of the third study did not provide enough information to characterize the overall outcome as positive or neutral. Consequently, there are insufficient data to provide an overall level of evidence assessment for the use of Cannabis for chemotherapy-induced N/V. Apparently, there are no published controlled clinical trials on the use of inhaled Cannabis for other cancer-related or cancer treatment–related symptoms.
  • An increasing number of trials are evaluating the oromucosal administration of Cannabis plant extract with fixed concentrations of cannabinoid components, with national drug regulatory agencies in Canada and in some European countries that issue approval for cancer pain.
  • At present, there is insufficient evidence to recommend inhaling Cannabis as a treatment for cancer-related symptoms or cancer treatment–related symptoms or cancer treatment-related side effects; however, additional research is needed.

Changes to This Summary (05/27/2016)

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Editorial changes were made to this summary.

This summary is written and maintained by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ® – NCI’s Comprehensive Cancer Database pages.

About This PDQ Summary

Purpose of This Summary

This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the use of Cannabis and cannabinoids in the treatment of people with cancer. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.

Reviewers and Updates

This summary is reviewed regularly and updated as necessary by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).

Board members review recently published articles each month to determine whether an article should:

  • be discussed at a meeting,
  • be cited with text, or
  • replace or update an existing article that is already cited.

Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.

The lead reviewers for Cannabis and Cannabinoids are:

  • Donald I. Abrams, MD (UCSF Osher Center for Integrative Medicine)
  • Nagi B. Kumar, PhD, RD, FADA (Fellow of the American Dietetic Association)

Any comments or questions about the summary content should be submitted to Cancer.gov through the NCI website’s Email Us. Do not contact the individual Board Members with questions or comments about the summaries. Board members will not respond to individual inquiries.

Levels of Evidence

Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Integrative, Alternative, and Complementary Therapies Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.

Permission to Use This Summary

PDQ is a registered trademark. Although the content of PDQ documents can be used freely as text, it cannot be identified as an NCI PDQ cancer information summary unless it is presented in its entirety and is regularly updated. However, an author would be permitted to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks succinctly: [include excerpt from the summary].”

The preferred citation for this PDQ summary is:

PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ Cannabis and Cannabinoids. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: http://www.cancer.gov/about-cancer/treatment/cam/hp/cannabis-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389198]

Images in this summary are used with permission of the author(s), artist, and/or publisher for use within the PDQ summaries only. Permission to use images outside the context of PDQ information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in this summary, along with many other cancer-related images, is available in Visuals Online, a collection of over 2,000 scientific images.

Disclaimer

The information in these summaries should not be used as a basis for insurance reimbursement determinations. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.

Contact Us

More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s Email Us.

Updated: May 27, 2016

This content is provided by the National Cancer Institute (www.cancer.gov)

Syndicated Content Details:
Source URL: http://www.cancer.gov/publishedcontent/syndication/65888.htm
Source Agency: National Cancer Institute (NCI)
Captured Date: 2013-09-14 09:06:03.0

Cannabis and Cannabinoids (PDQ®)–Patient Version

Overview

  • Cannabis , also known as marijuana, is a plant grown in many parts of the world which produces a resin containing compounds called cannabinoids. Some cannabinoids are psychoactive (acting on the brain and changing mood or consciousness) (see Question 1).
  • The use of Cannabis for medicinal purposes dates back to ancient times (see Question 3).
  • By federal law, the possession of Cannabis is illegal in the United States outside of approved research settings. However, a growing number of states, territories, and the District of Columbia have enacted laws to legalize medical marijuana (see Question 1).
  • In the United States, Cannabis is a controlled substance requiring special licensing for its use (see Question 1 and Question 3).
  • Cannabinoids are active chemicals in Cannabis that cause drug -like effects throughout the body, including the central nervous system and the immune system (see Question 2).
  • The main active cannabinoid in Cannabis is delta-9-THC. Another active cannabinoid is cannabidiol (CBD), which may relieve pain, lower inflammation, and decrease anxiety without causing the “high” of delta-9-THC (see Question 2).
  • Cannabinoids can be taken by mouth, inhaled, or sprayed under the tongue (see Question 5).
  • Cannabis and cannabinoids have been studied in the laboratory and the clinic for relief of pain, nausea and vomiting, anxiety, and loss of appetite (see Question 6 and Question 7).
  • Cannabis and cannabinoids may have benefits in treating the symptoms of cancer or the side effects of cancer therapies. There is growing interest in treating children for symptoms such as nausea with Cannabis and cannabinoids, although studies are limited (see Question 7).
  • Two cannabinoids (dronabinol and nabilone) are drugs approved by the U.S. Food and Drug Administration (FDA) for the prevention or treatment of chemotherapy -related nausea and vomiting (see Question 7 and Question 10).
  • Cannabis has been shown to kill cancer cells in the laboratory (see Question 6).
  • At this time, there is not enough evidence to recommend that patients inhale or ingest Cannabis as a treatment for cancer-related symptoms or side effects of cancer therapy (see Question 7).
  • Cannabis is not approved by the FDA for use as a cancer treatment (see Question 9).

Questions and Answers About Cannabis

  1. What is Cannabis?

    Cannabis , also known as marijuana, is a plant from Central Asia that is grown in many parts of the world today. The Cannabis plant produces a resin containing compounds called cannabinoids. Some cannabinoids are psychoactive (acting on the brain and changing mood or consciousness). In the United States, Cannabis is a controlled substance and has been classified as a Schedule I agent (a drug with a high potential for abuse and no currently accepted medical use).

    Clinical trials that study medicinal Cannabis in cancer are limited. To do research with Cannabis in the United States, researchers must file an Investigational New Drug (IND) application with the Food and Drug Administration (FDA), receive a Schedule I license from the Drug Enforcement Administration (DEA), and gain approval from the National Institute on Drug Abuse (NIDA).

    By federal law, the possession of Cannabis (marijuana) is illegal in the United States outside of approved research settings. However, a growing number of states, territories, and the District of Columbia have enacted laws to legalize medical marijuana. (See Question 4).

  2. What are cannabinoids?

    Cannabinoids are active chemicals in Cannabis that cause drug-like effects throughout the body, including the central nervous system and the immune system. They are also known as phytocannabinoids. The main active cannabinoid in Cannabis is delta-9-THC. Another active cannabinoid is cannabidiol (CBD), which may relieve pain and lower inflammation without causing the “high” of delta-9-THC.

    Cannabinoids may be useful in treating the side effects of cancer and cancer treatment.

    Other possible effects of cannabinoids include:

  3. What is the history of the medical use of Cannabis?

    The use of Cannabis for medicinal purposes dates back at least 3,000 years. It came into use in Western medicine in the 19th century and was said to relieve pain, inflammation, spasms, and convulsions.

    In 1937, the U.S. Treasury began taxing Cannabis under the Marijuana Tax Act at one dollar per ounce for medicinal use and one hundred dollars per ounce for non-medical use. The American Medical Association (AMA) opposed this regulation of Cannabis and did not want studies of its potential medicinal benefits to be limited. In 1942, Cannabis was removed from the U.S. Pharmacopoeia because of continuing concerns about its safety. In 1951, Congress passed the Boggs Act, which included Cannabis with narcotic drugs for the first time.

    Under the Controlled Substances Act passed by Congress in 1970, marijuana was classified as a Schedule I drug. Other Schedule I drugs include heroin, LSD, mescaline, methaqualone, and gamma-hydroxybutyrate (GHB).

    Although Cannabis was not believed to have any medicinal use, the U.S. government distributed it to patients on a case-by-case basis under the Compassionate Use Investigational New Drug (IND) program started in 1978. This program was closed to new patients in 1992.

    Researchers have studied how cannabinoids act on the brain and other parts of the body. Cannabinoid receptors (molecules that bind cannabinoids) have been discovered in brain cells and nerve cells in other parts of the body. The presence of cannabinoid receptors on immune system cells suggests that cannabinoids may have a role in immunity.

    Nabiximols (Sativex) is a Cannabis extract that contains delta-9-THC and cannabidiol (CBD). Nabiximols is approved in Canada (under the Notice of Compliance with Conditions) for relief of pain in patients with advanced cancer or multiple sclerosis.

  4. If Cannabis is illegal, how do some cancer patients in the United States use it?

    Though federal law prohibits the use of Cannabis, the map below shows the states and territories that have legalized Cannabis for medical purposes. Some other states have legalized only one ingredient in Cannabis, such as cannabidiol (CBD), and these states are not included in the map. Medical marijuana laws vary from state to state.

    Enlarge
    A map showing the U.S. states and territories that have approved the medical use of Cannabis.
A map showing the U.S. states and territories that have approved the medical use of Cannabis.
  • How is Cannabis administered?

    Cannabis may be taken by mouth or may be inhaled. When taken by mouth (in baked products or as an herbal tea), the main psychoactive ingredient in Cannabis (delta-9-THC) is processed by the liver, making an additional psychoactive chemical.

    When Cannabis is smoked and inhaled, cannabinoids quickly enter the bloodstream. The additional psychoactive chemical is produced in smaller amounts than when taken by mouth.

    A growing number of clinical trials are studying a medicine made from an extract of Cannabis that contains specific amounts of cannabinoids. This medicine is sprayed under the tongue.

  • Have any preclinical (laboratory or animal) studies been conducted using Cannabis or cannabinoids?

    Preclinical studies of cannabinoids have investigated the following:

    Antitumor activity

    • Studies in mice and rats have shown that cannabinoids may inhibit tumor growth by causing cell death, blocking cell growth, and blocking the development of blood vessels needed by tumors to grow. Laboratory and animal studies have shown that cannabinoids may be able to kill cancer cells while protecting normal cells.
    • A study in mice showed that cannabinoids may protect against inflammation of the colon and may have potential in reducing the risk of colon cancer, and possibly in its treatment.
    • A laboratory study of delta-9-THC in hepatocellular carcinoma (liver cancer) cells showed that it damaged or killed the cancer cells. The same study of delta-9-THC in mouse models of liver cancer showed that it had antitumor effects. Delta-9-THC has been shown to cause these effects by acting on molecules that may also be found in non-small cell lung cancer cells and breast cancer cells.
    • A laboratory study of cannabidiol (CBD) in estrogen receptor positive and estrogen receptor negative breast cancer cells showed that it caused cancer cell death while having little effect on normal breast cells. Studies in mouse models of metastatic breast cancer showed that cannabinoids may lessen the growth, number, and spread of tumors.
    • A laboratory study of cannabidiol (CBD) in human glioma cells showed that when given along with chemotherapy, CBD may make chemotherapy more effective and increase cancer cell death without harming normal cells. Studies in mouse models of cancer showed that CBD together with delta-9-THC may make chemotherapy such as temozolomide more effective.

    Stimulating appetite

    • Many animal studies have shown that delta-9-THC and other cannabinoids stimulate appetite and can increase food intake.

    Pain relief

    • Cannabinoid receptors (molecules that bind cannabinoids) have been studied in the brain, spinal cord, and nerve endings throughout the body of animals to understand their roles in pain relief.
    • Cannabinoids have been studied for anti-inflammatory effects that may play a role in pain relief.
    • Animal studies have shown that cannabinoids may prevent nerve problems (pain, numbness, tingling, swelling, and muscle weakness) caused by some types of chemotherapy.

    Nausea and vomiting

    • Cannabinoid receptors found in brain cells may have a role in controlling nausea and vomiting. Animal studies have shown that delta-9-THC and other cannabinoids may act on cannabinoid receptors to prevent vomiting caused by certain types of chemotherapy.

    Anxiety and sleep

    • Cannabinoid receptors found in the brain and other parts of the nervous system may be involved in controlling mood and anxiety.
    • Anti-anxiety effects of cannabidiol (CBD) have been shown in several animal models.
  • Have any clinical trials (research studies with people) of Cannabis or cannabinoid use by cancer patients been conducted?

    No clinical trials of Cannabis as a treatment for cancer in humans have been found in the CAM on PubMed database maintained by the National Institutes of Health.

    Cannabis and cannabinoids have been studied in clinical trials for ways to manage side effects of cancer and cancer therapies, including the following:

    Cancer

    Nausea and vomiting

    • Delta-9-THC taken by mouth: Two cannabinoid drugs approved in the United States are available under the names dronabinol and nabilone. Both dronabinol and nabilone are approved by the Food and Drug Administration (FDA) for the treatment of chemotherapy-related nausea and vomiting in patients who have not responded to standard therapy. Many clinical trials have shown that both dronabinol and nabilone worked as well as or better than some of the weaker FDA-approved drugs to relieve nausea and vomiting. Newer drugs given for chemotherapy-related nausea have not been directly compared with Cannabis or cannabinoids in cancer patients.
    • Inhaled Cannabis: Ten small trials have studied inhaled Cannabis for the treatment of chemotherapy-related nausea and vomiting. Various study methods and chemotherapy agents were used with mixed results. There is not enough information to interpret these findings.
    • Oral spray with delta-9-THC and cannabidiol (CBD): Nabiximols, a Cannabis extract given as a mouth spray, was shown in a small randomized, placebo-controlled, double-blinded clinical trial in Spain to treat chemotherapy-related nausea and vomiting.
    • There is growing interest in treating children for symptoms such as nausea with Cannabis and cannabinoids, although studies are limited. The American Academy of Pediatrics has not endorsed Cannabis and cannabinoid use because of concerns about brain development.

    Stimulating appetite

    • Delta-9-THC taken by mouth: A clinical trial compared delta-9-THC (dronabinol) and a standard drug (megestrol) in patients with advanced cancer and loss of appetite. Results showed that delta-9-THC was not as effective in increasing appetite or weight gain in advanced cancer patients compared with standard therapy. However, a clinical trial of patients with HIV /AIDS and weight loss found that those who took delta-9-THC had increased appetite and stopped losing weight compared with patients who took a placebo.
    • Inhaled Cannabis: There are no published studies of the effect of inhaled Cannabis on cancer patients with loss of appetite. Studies of healthy people who inhaled Cannabis showed that they consumed more calories, especially high-fat and sweet snacks.

    Pain relief

    • Combining cannabinoids with opioids: In a small study of 21 patients with chronic pain, combining vaporized Cannabis with morphine relieved pain better than morphine alone, while combining vaporized Cannabis with oxycodone did not produce significantly greater pain relief. These findings should be tested in further studies.
    • Delta-9-THC taken by mouth: Two small clinical trials of oral delta-9-THC showed that it relieved cancer pain. In the first study, patients had good pain relief as well as relief of nausea and vomiting and better appetite. A second study showed that delta-9-THC could be given in doses that gave pain relief comparable to codeine. An observational study of nabilone also showed that it relieved cancer pain along with nausea, anxiety, and distress when compared with no treatment. Neither dronabinol nor nabilone is approved by the FDA for pain management.
    • Cannabis plant extract medicine: A study of an extract of Cannabis that contained specific amounts of cannabinoids, which was sprayed under the tongue, found it was effective in patients with advanced cancer whose pain was not relieved by strong opioids alone. Patients who received the lower doses of cannabinoid spray showed markedly better pain control and less sleep loss compared with patients who received a placebo. Results showed that, for some patients, control of their cancer-related pain continued without needing higher doses of spray or higher doses of their other pain medicines.

    Anxiety and sleep

    • Inhaled Cannabis: A small case series found that patients who inhaled Cannabis had improved mood, improved sense of well-being, and less anxiety.
  • Have any side effects or risks been reported from Cannabis and cannabinoids?

    Adverse side effects of cannabinoids may include:

    Because Cannabis smoke contains many of the same substances as tobacco smoke, there are concerns about how inhaled cannabis affects the lungs. A study of over 5,000 men and women without cancer over a period of 20 years found that smoking tobacco was linked with some loss of lung function but that occasional and low use of cannabis was not linked with loss of lung function.

    Because use of Cannabis over a long time may have harmful effects on the endocrine and reproductive systems, rates of testicular germ cell tumors (TGCTs) in Cannabis users have been studied. Larger studies that follow patients over time and laboratory studies of cannabinoid receptors in TGCTs are needed to find if there is a link between Cannabis use and a higher risk of TGCTs.

    A review of bladder cancer rates in Cannabis users and non-users was done in over 84,000 men who took part in the California Men’s Health Study. Over 16 years of follow-up and adjusting for age, race/ethnic group and body mass index (BMI), rates of bladder cancer were found to be 45% lower in Cannabis users than in men who did not report Cannabis use.

    Both Cannabis and cannabinoids may be addictive.

    Symptoms of withdrawal from cannabinoids may include:

    • Irritability.
    • Trouble sleeping.
    • Restlessness.
    • Hot flashes.
    • Nausea and cramping (rarely occur).

    These symptoms are mild compared to withdrawal from opiates and usually lessen after a few days.

  • Are Cannabis or cannabinoids approved by the U.S. Food and Drug Administration for use as a cancer treatment in the United States?

    The U.S. Food and Drug Administration has not approved Cannabis or cannabinoids for use as a cancer treatment.

  • Are Cannabis or cannabinoids approved by the U.S. Food and Drug Administration for use as a treatment for cancer-related symptoms or side effects of cancer therapy?

    Cannabis is not approved by the U.S. Food and Drug Administration (FDA) for the treatment of any cancer-related symptom or side effect of cancer therapy.

    Two cannabinoids (dronabinol and nabilone) are approved by the FDA for the treatment of chemotherapy-related nausea and vomiting in patients who have not responded to standard therapy.

Current Clinical Trials

Check the list of NCI-supported cancer clinical trials for cancer CAM clinical trials on marijuana, nabilone, dronabinol and nabiximols that are actively enrolling patients.

General information about clinical trials is available from the NCI website.

About This PDQ Summary

About PDQ

Physician Data Query (PDQ) is the National Cancer Institute’s (NCI’s) comprehensive cancer information database. The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.

PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government’s center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.

Purpose of This Summary

This PDQ cancer information summary has current information about the use of Cannabis and cannabinoids in the treatment of people with cancer. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.

Reviewers and Updates

Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary (“Date Last Modified”) is the date of the most recent change.

The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board.

Clinical Trial Information

A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become “standard.” Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.

Clinical trials are listed in PDQ and can be found online at NCI’s website. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237).

Permission to Use This Summary

PDQ is a registered trademark. The content of PDQ documents can be used freely as text. It cannot be identified as an NCI PDQ cancer information summary unless the whole summary is shown and it is updated regularly. However, a user would be allowed to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks in the following way: [include excerpt from the summary].”

The best way to cite this PDQ summary is:

PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ Cannabis and Cannabinoids. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: http://www.cancer.gov/about-cancer/treatment/cam/patient/cannabis-pdq. Accessed <MM/DD/YYYY>.

Images in this summary are used with permission of the author(s), artist, and/or publisher for use in the PDQ summaries only. If you want to use an image from a PDQ summary and you are not using the whole summary, you must get permission from the owner. It cannot be given by the National Cancer Institute. Information about using the images in this summary, along with many other images related to cancer can be found in Visuals Online. Visuals Online is a collection of more than 2,000 scientific images.

Disclaimer

The information in these summaries should not be used to make decisions about insurance reimbursement. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.

Contact Us

More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s E-mail Us.

General CAM Information

Complementary and alternative medicine (CAM)—also referred to as integrative medicine—includes a broad range of healing philosophies, approaches, and therapies. A therapy is generally called complementary when it is used in addition to conventional treatments; it is often called alternative when it is used instead of conventional treatment. (Conventional treatments are those that are widely accepted and practiced by the mainstream medical community.) Depending on how they are used, some therapies can be considered either complementary or alternative. Complementary and alternative therapies are used in an effort to prevent illness, reduce stress, prevent or reduce side effects and symptoms, or control or cure disease.

Unlike conventional treatments for cancer, complementary and alternative therapies are often not covered by insurance companies. Patients should check with their insurance provider to find out about coverage for complementary and alternative therapies.

Cancer patients considering complementary and alternative therapies should discuss this decision with their doctor, nurse, or pharmacist as they would any therapeutic approach, because some complementary and alternative therapies may interfere with their standard treatment or may be harmful when used with conventional treatment.

Evaluation of CAM Approaches

It is important that the same rigorous scientific evaluation used to assess conventional approaches be used to evaluate CAM therapies. The National Cancer Institute and the National Center for Complementary and Integrative Health (NCCIH) are sponsoring a number of clinical trials (research studies) at medical centers to evaluate CAM therapies for cancer.

Conventional approaches to cancer treatment have generally been studied for safety and effectiveness through a rigorous scientific process that includes clinical trials with large numbers of patients. Less is known about the safety and effectiveness of complementary and alternative methods. Few CAM therapies have undergone rigorous evaluation. A small number of CAM therapies originally considered to be purely alternative approaches are finding a place in cancer treatment—not as cures, but as complementary therapies that may help patients feel better and recover faster. One example is acupuncture. According to a panel of experts at a National Institutes of Health (NIH) in November 1997, acupuncture has been found to be effective in the management of chemotherapy-associated nausea and vomiting and in controlling pain associated with surgery. In contrast, some approaches, such as the use of laetrile, have been studied and found ineffective or potentially harmful.

The NCI Best Case Series Program which was started in 1991, is one way CAM approaches that are being used in practice are being investigated. The program is overseen by the NCI’s Office of Cancer Complementary and Alternative Medicine (OCCAM). Health care professionals who offer alternative cancer therapies submit their patients’ medical records and related materials to OCCAM. OCCAM conducts a critical review of the materials and develops follow-up research strategies for approaches deemed to warrant NCI-initiated research.

Questions to Ask Your Health Care Provider About CAM

When considering complementary and alternative therapies, patients should ask their health care provider the following questions:

  • What side effects can be expected?
  • What are the risks associated with this therapy?
  • Do the known benefits outweigh the risks?
  • What benefits can be expected from this therapy?
  • Will the therapy interfere with conventional treatment?
  • Is this therapy part of a clinical trial?
  • If so, who is sponsoring the trial?
  • Will the therapy be covered by health insurance?

To Learn More About CAM

National Center for Complementary and Integrative Health (NCCIH)

The National Center for Complementary and Integrative Health (NCCIH) at the National Institutes of Health (NIH) facilitates research and evaluation of complementary and alternative practices, and provides information about a variety of approaches to health professionals and the public.

  • NCCIH Clearinghouse
  • Post Office Box 7923 Gaithersburg, MD 20898–7923
  • Telephone: 1-888-644-6226 (toll free)
  • TTY (for deaf and hard of hearing callers): 1-866-464-3615
  • E-mail: info@nccih.nih.gov
  • Website: https://nccih.nih.gov

CAM on PubMed

NCCIH and the NIH National Library of Medicine (NLM) jointly developed CAM on PubMed, a free and easy-to-use search tool for finding CAM-related journal citations. As a subset of the NLM’s PubMed bibliographic database, CAM on PubMed features more than 230,000 references and abstracts for CAM-related articles from scientific journals. This database also provides links to the websites of over 1,800 journals, allowing users to view full-text articles. (A subscription or other fee may be required to access full-text articles.)

Office of Cancer Complementary and Alternative Medicine

The NCI Office of Cancer Complementary and Alternative Medicine (OCCAM) coordinates the activities of the NCI in the area of complementary and alternative medicine (CAM). OCCAM supports CAM cancer research and provides information about cancer-related CAM to health providers and the general public via the NCI website.

National Cancer Institute (NCI) Cancer Information Service

U.S. residents may call the NCI Cancer Information Service toll free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 8:00 am to 8:00 pm. A trained Cancer Information Specialist is available to answer your questions.

Food and Drug Administration

The Food and Drug Administration (FDA) regulates drugs and medical devices to ensure that they are safe and effective.

  • Food and Drug Administration
  • 10903 New Hampshire Avenue
  • Silver Spring, MD 20993
  • Telephone: 1-888-463-6332 (toll free)
  • Website: http://www.fda.gov

Federal Trade Commission

The Federal Trade Commission (FTC) enforces consumer protection laws. Publications available from the FTC include:

  • Who Cares: Sources of Information About Health Care Products and Services
  • Fraudulent Health Claims: Don’t Be Fooled
  • Consumer Response Center
  • Federal Trade Commission
  • 600 Pennsylvania Avenue, NW
  • Washington, DC 20580
  • Telephone: 1-877-FTC-HELP (1-877-382-4357) (toll free)
  • TTY (for deaf and hard of hearing callers): 202-326-2502
  • Website: http://www.ftc.gov

Updated: May 27, 2016

This content is provided by the National Cancer Institute (www.cancer.gov)

Syndicated Content Details:
Source URL: http://www.cancer.gov/publishedcontent/syndication/122401.htm
Source Agency: National Cancer Institute (NCI)
Captured Date: 2013-09-14 09:06:06.0