Objective: Childhood and adolescent melanoma is rare but has been increasing. To gain insight into possible reasons underlying this observation, we analyzed trends in melanoma incidence diagnosed between the ages of 0 and 19 years among US whites by gender, stage, age at diagnosis, and primary site. We also investigated incidence trends by UV-B exposure levels.
Methods: By using Surveillance, Epidemiology, and End Results (SEER) program data (1973-2009), we calculated age-adjusted incidence rates (IRs), annual percent changes, and 95% confidence intervals for each category of interest. Incidence trends were also evaluated by using joinpoint and local regression models. SEER registries were categorized with respect to low or high UV-B radiation exposure.
Results: From 1973 through 2009, 1230 children of white race were diagnosed with malignant melanoma. Overall, pediatric melanoma increased by an average of 2% per year (95% confidence interval, 1.4%-2.7%). Girls, 15- to 19-year-olds, and individuals with low UV-B exposure had significantly higher IRs than boys, younger children, and those living in SEER registries categorized as high UV-B. Over the study period, boys experienced increased IRs for melanoma on the face and trunk, and females on the lower limbs and hip. The only decreased incidence trend we observed was among 15- to 19-year-olds in the high UV-B exposure group from 1985 through 2009. Local regression curves indicated similar patterns.
Conclusions: These results may help elucidate possible risk factors for adolescent melanoma, but additional individual-level studies will be necessary to determine the reasons for increasing incidence trends.
Keywords: SEER; UV; adolescence; cancer; childhood; epidemiology; incidence; melanoma; trends.