Incident testicular cancer in relation to using marijuana and smoking tobacco: A systematic review and meta-analysis of epidemiologic studies.

Background: Recent epidemiologic studies identified credible associations between marijuana smoking and risk of nonseminomatous testicular germ cell tumors (TGCTs), but did not distinguish exposure to cannabinoid compounds from exposure to other constituents of smoke.

Methods: We implemented a systematic review of scholarly literature followed by random effects meta-analysis to quantitatively synthesize published data relating incident TGCT to each of 2 exposure histories: ever using marijuana, and ever smoking tobacco.

Results: We identified four epidemiologic studies of marijuana use and 12 of tobacco smoking.