Pigmentation-related phenotypes and risk of prostate cancer

BACKGROUND: Solar ultraviolet radiation exposure has been inversely related to prostate cancer incidence and mortality, possibly mediated through vitamin D status. Pigmentation-related traits influence endogenous vitamin D synthesis and may alter risk of prostate cancer. METHODS: We examined prostate cancer in relation to hair and eye colour, and skin phototype in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort. Incident cancer was diagnosed in 1982 out of 20 863 men. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated from Cox proportional hazards models. RESULTS: Prostate cancer risk did not differ by eye colour or skin phototype. Men with naturally red hair were significantly less likely to develop prostate cancer (HR=0.46, 95% CI 0.24–0.89) than men with light brown hair (reference). CONCLUSION: The red hair phenotype, which results from polymorphisms in the melanocortin-1-receptor (MC1R) gene, is associated with lower risk of prostate cancer. This pigmentation-related trait may influence prostate cancer development either directly, through genetic effects or regulatory mechanisms related to MC1R, another nearby gene, or other pigmentation genes, or indirectly, through associations with other exposures such as sunlight or vitamin D status.