A population-level analysis on the association of cannabis use and urologic cancers.

Objectives: While cannabis is the most commonly used illicit substance, studies surrounding its association with urologic cancers are few and limited by small samples, uncontrolled confounders, or infrequent patient cannabis use. We aimed to investigate the association between cannabis use and risk of genitourinary malignancies, using a large claims database.

Methods: We retrospectively assessed United States adults between 2004 and 2024 in the TriNetX database. Those with prior genitourinary malignancies were excluded, and 2 cohorts were created based on having diagnoses of cannabis abuse/dependence or not. Cohorts were propensity score matched on demographic characteristics, tobacco use, nicotine dependence, substance-related disorders, and pertinent risk factors for each urologic malignancy, resulting in equal-sized cohorts. Final sample sizes varied following matching prior to analysis for each malignancy. Utilizing risk ratios, we assessed risk of developing bladder, kidney, prostate, upper tract, testis, and penile cancer any time after cannabis diagnosis.

Results: Following exclusion, 74,642 patients with and 4,709,585 without cannabis dependence or abuse were identified. After matching, cannabis abuse or dependence was significantly associated with increased risk of bladder (0.14% vs. 0.03%, RR = 4.21, 95% CI = [2.70, 6.57]), kidney (0.17% vs. 0.05%, RR = 3.70, 95% CI = [2.52, 5.43]), and prostate cancer (0.61% vs. 0.22%, RR = 2.80, 95% CI = [2.19, 3.58]). No significant association was found for upper tract, testis, or penile cancer.

Conclusions: We add to literature supporting the relationship between cannabis and bladder, kidney, and prostate cancer. As testis and penile cancer are relatively rare, however, we cannot exclude an association with these cancers. Future studies should investigate a dose-dependent relationship.