Cannabis use among cancer survivors: a systematic review and meta-analysis

The use of medical cannabis has been receiving growing attention as a potential therapeutic option for a diverse range of medical conditions, including cancer-related symptoms. The aim of this study was to estimate the prevalence of cannabis use among cancer survivors (post-treatment survivorship populations) and, secondarily, to compare these estimates with non-cancer control groups. Following PRISMA guidelines (PROSPERO CRD42024510013), we searched PubMed, Scopus, PsycINFO, Web of Science, CINAHL Complete, and grey literature through November 1, 2025. We included observational studies reporting the prevalence of cannabis use among cancer survivors (i.e., individuals with a history of cancer in survivorship/follow-up settings), regardless of whether a comparison group was available. In studies with comparator groups, controls were individuals without a history of cancer drawn from general population or other non-cancer reference samples. Random-effects (REML) models were used to pool prevalence estimates, while comparative odds ratios (ORs) were analyzed as a secondary outcome. Twenty-seven studies (176,072 participants; 21,025 cancer survivors and 155,047 controls) were included. Among survivors, pooled prevalences of cannabis use were 36.39% (95% CI 24.53–48.25) for lifetime use and 15.2% (95% CI 10.64–19.76) for past 30-day use, with lower estimates for current use (11.72%; 95% CI 5.02–18.43) and past-year use (7.96%; 95% CI 2.22–13.70). In studies with non-cancer controls, cancer survivors had lower odds of past 30-day use (OR 0.54; 95% CI 0.35–0.85; p = 0.01), however, no statistically significant differences were observed for current use (OR 0.93; 95% CI 0.79–1.10; p = 0.42), past-year (OR 0.40; 95% CI 0.12–1.30; p = 0.13), and lifetime cannabis use (OR 0.98; 95% CI 0.70–1.37; p = 0.92). Cannabis use is common among cancer survivors. Compared with non-cancer populations, survivors showed lower odds of recent (past 30-day) use, while no statistically significant differences were observed for current, past-year, or lifetime cannabis use. These findings underscore the need for open, evidence-based counseling about potential benefits, risks, and safe use in survivorship care.