Epidemiology of Anorectal Melanoma in the United States: 1992 to 2011

Abstract

Background: Anorectal melanoma is a rare type of malignant melanoma and thus the epidemiology of patients with this tumor has been poorly defined.

Objective: To describe the epidemiology of anorectal melanoma in the United States.

Methods and materials: We obtained case and population data from the Surveillance, Epidemiology, and End Results 13 Registries Database (SEER 13) between 1992 and 2011 using rectal diagnostic codes C20.9 to 21.8 and ICD-O-3 melanoma codes 8720 to 8721 and 8742 to 8746.

Results: There were 260 primary anorectal melanomas in SEER 13 from 1992 to 2011, occurring mostly in the rectum. The incidence of anorectal melanoma was higher among women than men with the highest rates occurring among white Hispanics ages 65 to 74 years. During this time period, the age-adjusted incidence rates rose significantly (p < .05) for both women and men with estimated annual percentage changes of 3.02% and 5.08%, respectively. Overall and melanoma-specific survival was poor irrespective of gender or ethnicity.

Conclusion: Anorectal melanoma in the United States is increasing in both men and women, with the highest rates in elderly Hispanic white women. Hispanic whites were more likely to develop anorectal melanoma than non-Hispanic whites, suggesting that this population may be targeted for screening interventions. These results warrant further investigation to better understand the gender, racial, ethnic, and geographic variations for anorectal melanomas.