Abstract 866: Changing anatomic site trends of melanoma in the United States among young women
Authors: Bradford Porcia T. , Anderson William F. , Purdue Mark P. , Goldstein Alisa M. , Tucker Margaret A. 
Published: February 2011

Cutaneous malignant melanoma incidence rates have been increasing among young women in the United States. Given that tan-seeking behaviors have increased ultraviolet radiation exposures in anatomic sites usually covered by clothing, i.e., trunk among women, we further assessed melanoma incidence trends by gender and anatomic site. Case and population data among Whites were obtained from the Surveillance, Epidemiology, and End Results Tumor Registries (SEER 9, 1975-2006). Age-period-cohort models were used to assess age, calendar-period, and birth-cohort effects. Net drift, the sum of linear trends in the period and cohort effects, was used to show differential secular trends due to period and/or cohort effects such as screening, case ascertainment, sun exposure, etc. Longitudinal age trend (LAT), the sum of the linear trends in the age and period effects, was used to show differential age-related biological effects. There were 105,829 melanomas diagnosed from 1975 through 2006 in the SEER 9 Registries. The overall age-adjusted incidence rate (IR) was 17.70 per 100,000, with a male to female incidence rate ratio (IRR) of 1.40 (p&lt;0.001). The mean and median ages at diagnosis were slightly higher among males than females overall (59 vs 52 years, respectively). Age-specific IRs were greater among women than men prior to age 40 years, after which rates were greater for men. Overall, the most common anatomic sites for melanoma were the trunk for men (8.30 per 100,000) and lower extremity for women (4.91 per 100,000). However, the relative distributions of melanomas shifted by anatomic site during our study period. Among men, IRRs rose 24.65% for the face/head/neck and 27.26% for the upper extremity, but fell −6.84% for the lower extremity when compared to melanomas of the trunk. Conversely, among women, IRRs decreased for all anatomic sites relative to the trunk. The highest net drift was for melanoma of the female trunk [3.78% per calendar year (95% CI, 3.52-4.05)]. LAT per year of attained age was highest for male face/head/neck melanoma (10.27% per year, 95% CI, 9.86-10.68) and lowest for female trunk melanoma (5.41% per year, 95% CI, 5.10-5.72). The combination of high net drift and low LAT shows that melanomas of the trunk are rising preferentially among young women. In conclusion, we present evidence for changing melanoma anatomic trends in the United States. Female trunk melanomas are increasing relative to all other female sites, suggesting different trends in carcinogenic exposures or etiologic differences by melanoma anatomic site. Furthermore, these secular shifts are occurring among young women. Given the fact that age-period-cohort analyses of melanoma incidence reveal that incidence rates may continue to rise in the U.S., further surveillance and analytical studies are needed.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 866.