Decreased risk of prostate cancer after skin cancer diagnosis: a protective role of ultraviolet radiation?

Ultraviolet radiation causes skin cancer but may protect against prostate cancer. The authors hypothesized that skin cancer patients had a lower prostate cancer incidence than the general population. In the southeastern part of the Netherlands, a population-based cohort of male skin cancer patients diagnosed since 1970 (2,620 squamous cell carcinomas, 9,501 basal cell carcinomas, and 1,420 cutaneous malignant melanomas) was followed up for incidence of invasive prostate cancer until January 1, 2005, within the framework of the Eindhoven Cancer Registry. The incidence rates of prostate cancer among skin cancer patients were compared with those in the reference population, resulting in standardized incidence ratios. Skin cancer patients were at decreased risk of developing prostate cancer compared with the general population (standardized incidence ratio (SIR) = 0.89, 95% confidence interval (CI): 0.78, 0.99), especially shortly after diagnosis. The risk of advanced prostate cancer was significantly decreased (SIR = 0.73, 95% CI: 0.56, 0.94), indicating a possible antiprogression effect of ultraviolet radiation. Patients with a skin cancer in the chronically ultraviolet radiation-exposed head and neck area (SIR = 0.84, 95% CI: 0.73, 0.97) and those diagnosed after the age of 60 years (SIR = 0.86, 95% CI: 0.75, 0.97) had decreased prostate cancer incidence rates. These results support the hypothesis that ultraviolet radiation protects against prostate cancer.