A reader in the UK asks: “Are there any studies or research notes on the use of medical marijuana while undergoing immunotherapy for the treatment of cancer?”

The short answer from Joe D. Goldstrich, MD, FACC, June 17, 2017:

“THC is sometimes used to down-regulate the immune system (auto-immune diseases). Based on this article and other research, in my opinion, it would not be appropriate to use THC in conjunction with immune therapies. I have worked with one patent who, despite my advice, decided to use cannabinoids with Keytruda, an immune therapy. His glioblastoma continued to grow. I have searched the medical literature for research on combining cannabinoids with immune therapies, but have found no published studies.”

In March of this year, as Dr. Goldstrich began consulting with the patient referred to above, he wrote a longer note on the possible pros and cons of combining cannabinoids with Keytruda:

Concerning concomitant use of cannabinoids and immunotherapies in the treatment of cancer

One of the most exciting new cancer therapies is called immunotherapy. Scott Pelley explored this approach in a 60 Minutes episode in May 2016. 

Now, TV commercials abound with enticing messages like “A chance to live longer… Keytruda” and many patients are being offered immunotherapy as a primary treatment for their cancer.

There is preliminary evidence to support the concomitant use of cannabinoids with chemotherapy and radiation in the treatment of cancer, and I always encourage patients to consider combining cannabinoids with their traditional therapy. Some of the best responses that I have seen in my work with cancer patients have been in those who have combined cannabinoids with their chemotherapy and radiation.



Can cannabinoids complement immunotherapies as they do with radiation and other chemotherapies? Cannabinoids are known to down-regulate the immune system and in this regard have been helpful for some patients with autoimmune disease, as suggested by the following:





If the purpose of the immunotherapy is to stimulate the immune system so that it can attack the cancer, wouldn’t it be counterproductive to use these immunotherapies with known down regulators of the immune system? That’s my basic question. Initially I suggested that patients use the immunotherapies and if needed down the road, the cannabinoids could be added. However, after seeing this New York Times article  and realizing that these immunotherapies are not benign, I have been less optimistic about this approach.

I’ve asked prominent researchers from around the world their opinion and no one has an authoritative answer. I got replies like, “your guess is as good as mine because there is no data.”  Currently, I have one patient who has been combining the two therapies, but it’s too early to know anything definitive about their response.

Using cannabinoids in the fight against cancer is an ongoing educational process.