Age-dependent associations between androgenetic alopecia and prostate cancer risk

Background: Both prostate cancer and androgenetic alopecia are strongly age-related conditions that are considered to be androgen dependent, but studies of the relationship between them have yielded inconsistent results. We aimed to assess whether androgenetic alopecia at ages 20 and 40 years are associated with risk of prostate cancer. Methods: At a follow-up of the Melbourne Collaborative Cohort Study, men were asked to assess their hair pattern at ages 20 and 40 years relative to eight categories in showcards. Cases were men notified to the Victorian Cancer Registry with prostate cancer diagnosed between cohort enrollment (1990-1994) and followup attendance (2003-2009). Flexible parametric survival models were used to estimate age-varying HRs and predicted cumulative probabilities of prostate cancer by androgenetic alopecia categories. Results: Of 9,448 men that attended follow-up and provided data on androgenetic alopecia, we identified 476 prostate cancer cases during a median follow-up of 11 years four months. Cumulative probability of prostate cancer was greater at all ages up to 76 years, for menwith vertex versus no androgenetic alopecia at age of 40 years. At age of 76 years, the estimated probabilities converged to 0.15. Vertex androgenetic alopecia at 40 years was also associated with younger age of diagnosis for prostate cancer cases. Conclusions: Vertex androgenetic alopecia at age of 40 years might be a marker of increased risk of earlyonset prostate cancer. Impact: If confirmed, these results suggest that the apparently conflicting findings of previous studies might be explained by failure to adequately model the age-varying nature of the association between androgenetic alopecia and prostate cancer. © 2012 American Association for Cancer Research.