Time trends in incidence of cutaneous melanoma by detailed anatomical location and patterns of ultraviolet radiation exposure: a retrospective population-based study.

Given the wide public health implications of the melanoma epidemic, ultraviolet radiation (UVR) exposure patterns contributing to cutaneous melanoma development should be clearly identified. To describe time trends of anatomic sites of melanoma using a UVR exposure model based on clothing and sun habits, we reviewed the medical records of all patients diagnosed with primary invasive melanoma or melanoma in situ (MIS) during the years 1977-78, 1983-84, 1989-90, 1995-96, and 2000-01 (n=3058) in one healthcare region of Sweden. Age-standardized incidence rates and relative risks (RRs) of melanoma by calendar period were estimated for intermittent and chronic UVR exposure sites. From 1977-78 to 2000-01, the incidence rates of all melanomas at intermittent UVR exposure sites increased both among men (7.8-16.5/10 person-years) and among women (7.6-14.6/10 person-years), with a sex-adjusted and age-adjusted RR of 2.1 [95% confidence interval (CI) 1.8-2.4, Ptrend<0.0001]. This increase was evident for both invasive melanoma and MIS. Melanoma at chronic sites increased among men from 1.7 to 2.3/10 person-years, and among women from 1.4 to 1.8/10 person-years, with a corresponding adjusted RR of 1.4 (95% CI 1.0-1.9, Ptrend=0.01), driven primarily by MIS. For melanomas at intermittent UVR exposure sites, the male sex was positively associated with central (core) areas (chest, back, neck, shoulders, thighs; RR 1.7, 95% CI 1.5-1.9), but negatively associated with peripheral areas (lateral arms, lower legs, dorsum of feet; RR 0.3, 95% CI 0.3-0.4), compared with the female sex. Sex-specific intermittent UVR exposure patterns drove the observed increase in melanoma incidence, whereas chronic UVR exposure contributed less.