Association between lifetime co-use of classic psychedelics and cannabis and prostate cancer diagnosis among US adults 50 years and older

Prostate cancer is the second leading cause of cancer-related deaths among U.S. men. While cannabis and classic psychedelics gain attention for symptom management in oncology, their associations with prostate cancer remain unexplored. This study evaluates associations between lifetime classic psychedelic and cannabis use with prostate cancer diagnoses among older U.S. adults using 2015-2019 National Survey on Drug Use and Health (NSDUH) data. A nationally representative sample of 19,460 males (weighted N = 50,842,517) aged ≥ 50 years was included in the analysis. Participants were categorized as: cannabis-only users, classic psychedelic-only users, co-users, and non-users. The primary outcome was self-report of physician-diagnosed prostate cancer. Multivariable logistic regression models estimated the adjusted odds ratios (AORs) for lifetime use and prostate cancer, adjusting for socio-demographic, behavioral, and clinical covariates, and analyses further stratified by age. Among participants, 3.9% reported prostate cancer. Exclusive classic psychedelic use was associated with increased odds of prostate cancer (AOR: 2.62, 95% CI: 1.31-5.22, p < 0.01) versus non-users. Among those ≥ 65, classic psychedelic-only use was also associated with higher odds (AOR: 3.60, 95% CI: 1.71-7.55, p < 0.01) of prostate cancer than non-users. Classic psychedelic-only users had higher odds of prostate cancer versus co-users (AOR: 4.58, 95% CI: 1.89-11.1, p < 0.01). This study identified a novel association between classic psychedelic use and prostate cancer in older adults. Future research should explore reasons for use, potential biological mechanisms, and consider longitudinal studies to clarify causality.