Cancer Therapy Advisor: How do you counsel patients asking about cannabis use?

Dr Paice: The 2 most important points that I counsel patients about are the 3 the types of cannabis that exist and the different routes of administration. The 3 different types of cannabis are: our body’s own endogenous cannabinoids, the phytocannabinoids, which is what most people are doing when they are smoking cannabis, and synthetic cannabinoids like dronabinol (Marinol). The reason it’s so important to talk about those 3 types is because patients may be listening to reports that are not specific as to the type studied.

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There are more data about synthetic cannabinoids, but there are a few studies about the phytocannabinoids for nerve pain, particularly in cancer and in HIV. The reason that there are not many studies about the phytocannabinoids is because up until recently, the National Institutes of Health (NIH) was not awarding many grants.

The different routes of administration are also important for patients to understand. Cannabis can be inhaled via a joint or vaporizer, which may limit the amount of harsh chemicals that might be inhaled. The ingested route includes eating food substances that contain cannabis oil, and there are oils that can be applied topically at the site of pain. We really have data only about inhaled forms with respect to analgesic efficacy, but the challenge about oils is we have no data on those.

We do have a bit of knowledge about the onset, which has important implications for patients. When you smoke or inhale, you get blood levels in 2 to 5 minutes, but when you ingest it, the bioavailability is delayed and the onset can be 2 to 6 hours. This has been causing some difficulties in states where cannabis is legal recreationally where tourists are consuming more cannabis because they are not feeling immediate effects.

Cancer Therapy Advisor: Anecdotally, for what are patients using phytocannabinoids and synthetic cannabinoids, and do they think these agents have been helpful?

Dr Paice: Dronabinol is now approved by the U.S. Food and Drug Administration for the use of AIDS-related anorexia. I do find for some patients that dronabinol can be useful for improving appetite, and I certainly see that with the phytocannabinoids too.

The benefits that patients report from using phytocannabinoids include pain control, improved appetite, anxiolysis, and improved sleep. Those are the most common uses that I hear anecdotally from patients. Some patients tell me taking a few puffs before bedtime helps to relax and reduce pain.

Cancer Therapy Advisor: Do you think that the approval of these ballot initiatives is a positive step toward increased access to cannabis for patients seeking additional symptom relief?

Dr Paice: There are insufficient data on the use of medical cannabis in patients with cancer. We would like to see more data about both the benefits and the potential harms. In all of the studies conducted in patients with cancer pain, they were studying patients who were already taking opioids, and as a result, we do not know whether cannabis should be used in the first-line setting.                                 


  1. Paice JA, Portenoy R, Lacchetti C, et al. Management of chronic pain in survivors of adult cancers: American Society of Clinical Oncology clinical practice guideline. J Clin Oncol. 2016;34(27):3325-45.