Muscle-building supplement use and increased risk of testicular germ cell cancer in men from Connecticut and Massachusetts

Background: No analytic epidemiological study has examined the relationship between use of muscle-building supplements (MBSs) and testicular germ cell cancer (TGCC) risk. Methods: We conducted a population-based case–control study including 356 TGCC cases and 513 controls from Connecticut and Massachusetts. Results: The odds ratio (OR) for ever use of MBSs in relation to risk of TGCC was significantly elevated (OR=1.65, 95% confidence interval (CI): 1.11–2.46). The associations were significantly stronger among early users, men with more types of MBSs used, and longer periods of use. Conclusions: MBS use is a potentially modifiable risk factor that may be associated with TGCC.