Cannabis use and testicular germ cell tumour subtypes in the french nationwide TESTIS case-control study

Testicular germ cell tumours (TGCTs) are the most common malignancy among young men, and their rapidly increasing incidence suggests a role for modifiable risk factors. The role of increasingly prevalent cannabis use, particularly during developmental periods before biological maturation, in TGCT etiology remains unclear.

The association between cannabis use in adolescence and early adulthood and TGCT was assessed in a nationwide hospital-based case-control study in France (454 cases, 670 controls). Exposure was characterized by timing and frequency, including persistent use. Weekly-equivalent exposure scores were used to approximate exposure-response. Conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs), overall and by histological subtype.

Cannabis use was not consistently associated with TGCT risk overall. Associations varied by timing and histological subtype. Early adulthood daily use was associated with increased TGCT risk overall (OR _baseline=1.50, CI 1.02-2.19) and with seminoma (OR _baseline=2.02, CI 1.22, 3.33; OR _adjusted=1.93, CI 1.13-3.31), adjusted for tobacco, alcohol, and education. Exposure-response was observed in early adulthood (p-trend = 0.046), particularly for seminoma (p-trend = 0.016). Weekly use across 12-25 years was associated with increased TGCT risk (OR _adjusted=1.85, CI 1.11-3.07), with similar patterns for seminoma (OR _adjusted=2.29, CI 1.09-4.79). No associations were observed in adolescence or for non-seminoma.

Findings support an effect of cannabis use during early adulthood on TGCT risk with significant dose-response relationships and stronger associations for daily use, particularly for seminoma; however, subtype results require cautious interpretation and independent confirmation.