Updated Research: Cannabis Use During Immunotherapy

Previous studies suggested that patients receiving immunotherapy and using cannabis have worse clinical outcomes and reduced overall survival compared to patients that don’t use cannabis. As a result of this, we have been hesitant to recommend cannabis to patients on immunotherapy treatment.

However, a new study in the European Journal of Cancer (1) calls the previous studies into question.  The researchers found no deleterious effects of cannabis on the activity of the immunotherapy drug, pembrolizumab, as first-line monotherapy for advanced non-small cell lung cancer. The authors believe the more adverse outcomes in those using cannabis are most likely attributed to the study design.  For example, the previous studies included patients with various cancers, treatment regimens, and lines of therapy and patients were provided immunotherapy shortly before death.  The authors conclude that “under these circumstances, the use of cannabis is often a mere surrogate for high-burden symptomatic disease.”

While this new study provides some relief to those undergoing immunotherapy and wanting to incorporate cannabis into their daily regimens, further studies will be needed in patients with various forms of cancer and on other immunotherapy drugs to determine whether cannabis can interfere with the drug’s efficacy.  In the meantime, for those using cannabis while on immunotherapy, it would be best to start low and only use enough to get the desired effect.

For a layperson’s (and excellently written overview), refer to the recent @projectcbd post authored by Nate Seltenrich on 1/17/2023. Original paper cite: (1) The use of medical cannabis concomitantly with immune checkpoint inhibitors in non-small cell lung cancer: A sigh of relief? Eur J Cancer. 2022 Nov 29;180:52-61.