As of 2019, 33 states and District of Columbia have legalized the use of marijuana for medical purposes. Marijuana comes from the dried buds and leaves of the Cannabis sativa plant and many cancer patients report marijuana to have beneficial effects in suppressing chemotherapy- induced nausea and vomiting, increasing appetite, relieving pain, and soothing anxiety . The two most studied components of marijuana are delta-9-tetrahydrocannabinol (commonly known as THC) and cannabidiol (CBD). THC is the chemical compound that elicits the “high” feeling experienced by marijuana users and is reported to relieve pain and nausea. CBD is a non-psychoactive component and is reported to treat seizures and reduce anxiety . Marijuana can be administered orally (often in the form of baked goods) or smoked. If administered orally, THC may takes hours to absorbed and individuals may sometimes over- administer marijuana due to not feeling the effects right away. Individuals smoking marijuana can feel the effects almost immediately and THC can be detected in the blood within 6 to 10 minutes .
Two marijuana- based drugs are currently approved for the treatment of chemotherapy- induced nausea and vomiting (CINV): Dronabinol (Marinol®) and Nabilone (Cesamet®). Dronabinol is gelatin capsule containing THC and Nabilone is a man-made cannabinoid that mimics THC . Although both drugs are effective treatment for CINV, they have unfavorable side effects, which include dizziness, drowsiness, euphoria, and lightheadedness, to name a few [2, 4]. Given the availability of other drugs for the prevention of CINV, the American Society of Clinical Oncology only recommend Dronabinol and Nabilone for patients intolerant to those drugs .
Evidence supporting the benefits of marijuana use in cancer patients is largely anecdotal and, to date, only a few scientific studies on the efficacy of marijuana have been published. In one study, participants suffering from CINV were randomized to receive oromucosal spray of placebo or a whole-plant cannabis- based medicine (CBM) containing THC and CBD. Five out of the seven (71.4%) patients receiving CBM exhibited complete response, defined as having no vomiting, in comparison to two out of nine (22.2%) patients in the placebo group . Two studies evaluated the effects of smoked THC on CINV and showed contradicting results. In one study, 15 participants received oral and smoked THC and 14 of the participants reported reduction in nausea and vomiting . Another studies with eight participants showed oral and smoked THC to be ineffective in reducing nausea and vomiting . In each of the studies mentioned above, the number of study participants is extremely small and should be interpreted with caution. In addition, there has been no evidence that other illegal substances have proven to have a positive effect, so physicians should be sure to enlist the help of potentially a saliva drug test, to rule out use of other prohibited substances.
Given the scarcity of scientific evidences for the effectiveness of marijuana on CINV, the American Society of Clinical Oncology concluded, “evidence remains insufficient for a recommendation regarding medical marijuana for the prevention of nausea and vomiting in patient with cancer who receive chemotherapy or radiation therapy” . In contrast to Dronabinol and Nabilone, for which the doses are
precisely defined, such information is not available for medical marijuana. Patients using medical marijuana lack guidance with regards to the dose to self- administer. Furthermore, the concentration of active ingredients (i.e. THC and CBC) in marijuana varies depending on marijuana preparation methods. Additionally, many of the same carcinogens found in tobacco are also found in smoked cannabis and they included 4- aminobiphenyl, arsenic, benzene, cadmium, formaldehyde, and lead . Therefore, similar to tobacco use, the use of medical marijuana may inadvertently increase the risk of developing cancer. Other side effects of medical marijuana include the feeling of euphoria (“high”), lower control of movement, and feelings of anxiety and paranoia .
Many other FDA- approved drugs are available for the treatment of chemotherapy-induced nausea and vomiting (CINV) that makes medical marijuana unnecessary. Until more scientific evidence show the effectiveness of medical marijuana, I personally believe the potential risk of marijuana use outweigh benefits.
- Mack, A. and J. Joy, in Marijuana as Medicine? The Science Beyond the Controversy. 2000, National Academies Press (US)
Copyright 2001 by the National Academy of Sciences. All rights reserved.: Washington (DC).
- Kramer, J.L., Medical marijuana for cancer. CA: A Cancer Journal for Clinicians, 2015. 65(2): p. 109-122.
- American Cancer Society. Marijuana and Cancer. March 16, 2017
; Available from: https://www.cancer.org/treatment/treatments-and-side-effects/complementary-and-alternative-medicine/marijuana-and-cancer.html.
- Machado Rocha, F.C., et al., Therapeutic use of Cannabis sativa on chemotherapy-induced nausea and vomiting among cancer patients: systematic review and meta-analysis. Eur J Cancer Care (Engl), 2008. 17(5): p. 431-43.
- Hesketh, P.J., et al., Antiemetics: American Society of Clinical Oncology Clinical Practice Guideline Update. J Clin Oncol, 2017. 35(28): p. 3240-3261.
- Duran, M., et al., Preliminary efficacy and safety of an oromucosal standardized cannabis extract in chemotherapy-induced nausea and vomiting. Br J Clin Pharmacol, 2010. 70(5): p. 656-63.
- Chang, A.E., et al., Delata-9-tetrahydrocannabinol as an antiemetic in cancer patients receiving high-dose methotrexate. A prospective, randomized evaluation. Ann Intern Med, 1979. 91(6): p. 819-24.
- Chang, A.E., et al., A prospective evaluation of delta-9-tetrahydrocannabinol as an antiemetic in patients receiving adriamycin and cytoxan chemotherapy. Cancer, 1981. 47(7): p. 1746-51.