Basal-cell carcinoma incidence and associated risk factors in U.S. women and men.

There is a paucity of data on basal-cell carcinoma (BCC) in the United States, since most national registries do not collect information on BCC. We evaluated BCC incidence trends and associated risk factors for BCC in 140,171 participants from a U.S. female cohort, the Nurses' Health Study (1986-2006), and a U.S. male cohort, the Health Professionals' Follow-up Study (1988-2006). Age-adjusted BCC incidence rates increased from 519 cases per 100,000 person-years to 1,019 cases per 100,000 person years for women and increased from 606 cases per 100,000 person-years to 1,488 cases per 100,000 person-years for men during the follow-up period. Cox proportional hazards analysis identified the following phenotypic risk factors for BCC in both cohorts: family history of melanoma, blond or red hair colors, higher number of extremity moles, higher susceptibility to sunburn as a child/adolescent, and higher lifetime number of severe/blistering sunburns. The multivariate-adjusted risk ratio for the highest quintile of cumulative midrange ultraviolet B flux exposure versus the lowest quintile was 3.18 (95% confidence interval: 2.70, 3.76) in women and 1.90 (95% confidence interval: 1.57, 2.29) in men. BCC incidence was generally higher in men than in women, and BCC risk was strongly associated with several phenotypic and exposure factors, including midrange ultraviolet B radiation, in our study populations.