Epidemiologic Support for Melanoma Heterogeneity Using the Surveillance, Epidemiology, and End Results Program

Abstract

TO THE EDITOR Several studies have used evidence evaluating genetic alterations (Curtin et al., 2005) and anatomic location (Whiteman et al., 2003) to support theories that melanoma is a heterogeneous disease with differing etiologies. Using data from the large-scale, population-based Surveillance, Epidemiology, and End Results Program (SEER) of the National Cancer Institute, we examined whether age-specific incidence patterns separated by sex and site would reveal distinct melanoma subgroups. Age, sex, and anatomic site were abstracted for all microscopically confirmed, first invasive cutaneous melanomas among non-Hispanic white adults collected by the SEER 17 Registry Program from 2000 to 2004. Incidence rates, summarized across 5-year age groups, were plotted by age at diagnosis on a log-log scale, and age distribution curves were created. Detailed materials and methods are available in Supplementary Materials and Methods. After excluding 15 cases missing age at diagnosis, 48,673 cases were available for analysis (Table 1). Fifty-six percent of patients were male, and the mean age at diagnosis was 57.0 years. Forty-one percent of all melanomas occurred among those 40–59 years of age. However, the age-specific incidence rate peaked among people aged 70–79 years, who had an incidence rate 5.9 times higher (95% confidence intervals, 5.6–6.2) than those aged 20–29 years. The incidence rate ratio for females compared to males was 0.7 (95% confidence intervals, 0.7–0.7). Forty-three percent of melanomas were located on the extremities, 34% on the trunk, 12% on the face/ears, 7% on the scalp/neck, and 4% at other/unclassified sites.