Cancer and cancer chemotherapy cause nausea and vomiting, pain, neuropathy, depression, sleep disorders, and other debilitating symptoms.¹ These symptoms often develop during treatment and can persist after cessation of chemotherapy, severely impacting long-term quality of life.² With more survivors than ever, and survivors living longer lives,³ it is important to address these symptoms to maximize survivors’ quality of life.

Despite limited randomized clinical trials, cannabis shows promise to improve many symptoms of cancer and its treatments.^4,5 Social acceptance is also greatly increasing its use, despite lack of scientific evidence of safety and efficacy. In fact, in one community oncology clinic, 18.3% of patients with cancer reported using cannabis in 2017.⁶ In a Canadian study conducted in 2017, before cannabis was legalized in that country, 18% of patients with cancer used cannabis, often to relieve cancer-related pain, nausea, or other cancer symptoms.⁷ Unfortunately, although 80% of clinicians are discussing cannabis (i.e., medical marijuana) with patients, only 30% feel adequately informed to make recommendations about its use.⁸ It is crucial that scientific research on cannabis be accelerated to match patient demand. Only then will clinicians and patients have reliable safety and efficacy data to inform decisions that integrate information on patient symptoms, type of cannabis, delivery system, patient preference, dose, duration, and side-effects/adverse events.

This review describes how cannabis might modulate the most common and debilitating symptoms of cancer and its treatments in the context of cancer treatment, palliative care, and survivorship. While other reviews have examined the literature on medical cannabis related to cancer care (e.g., ^4,5,9–12), we further explore cannabis in animal models and in other medical fields and cautiously extrapolate these findings to supportive and palliative care in cancer in humans. We urge patients and clinicians to recognize the potential drawbacks and dangers of cannabis, including allergic reactions, addiction/dependence, side effects, and interference with other medications. Nevertheless, we conclude that cannabis, in combination with guideline-based treatment regimens, tends to exhibit potential benefits that outweigh its risks.