Cannabis Use by Veterans and Potential Interactions With Antineoplastic Agents: Analysis and Literature Review

Extensive research exists investigating medicinal uses of cannabis products in patients with malignancies, though it is largely unknown how cannabis use may affect the efficacy of antineoplastics. Like many antineoplastic agents, cannabis is metabolized by cytochrome P450, leading to potential interactions. This observational study sought to identify the prevalence of cannabis use in patients with a malignancy at the Veterans Affairs Memphis Healthcare System and analyze the potential for interactions between various products and the antineoplastic agents the patients received.

A retrospective review of electronic health records was completed for patients who used cannabis products during treatment and accepted the invitation to complete a survey during January 2024. Prescribed antineoplastic medications for each patient were recorded, and data were compiled and analyzed for potential interactions.

A total of 132 patients agreed to participate in the survey, and 50 (38%) acknowledged use of cannabis products within the previous 90 days. Forty-five patients (90%) who used cannabis within 90 days were male, and 29 patients (58%) were aged 60 to 65 years. Thirty-five patients (70%) predominantly inhaled cannabis. Twenty-one patients (42%) had chemotherapy, the most common treatment, 19 patients (38%) had immunotherapy, 12 patients (24%) used targeted therapy, and 10 patients (20%) used endocrine therapy.

This analysis found a notable prevalence of patients with cancer concurrently using cannabis while being prescribed an antineoplastic. The results of this study suggest a potential decrease in the efficacy of immunotherapy and endocrine therapy and an increase in toxicity with chemotherapy and targeted agents when used alongside cannabis products.