(ChemotherapyAdvisor) – The annual incidence of anorectal melanoma is increasing at a significantly higher rate in men than in women, who have significantly higher incidence rates overall; however, no survival advantage by gender can be detected, according to a study that described the epidemiology of the disease over an 18-year period presented at the Society for Melanoma Research 2012 Congress, Hollywood, CA.

The data in men suggest “either a true increase in incidence or improved diagnosis,” noted Meg R. Gerstenblith, MD, of the Department of Dermatology, University Hospitals Case Medical Center, Cleveland, OH, USA, and colleagues. Anorectal melanoma, a rare subtype of melanoma, often presents at a late stage and has a poor prognosis. “Given its rarity, the epidemiology of anorectal melanoma is not well characterized,” they stated.

The investigators obtained case and population data for 1992 to 2009 from the Surveillance Epidemiology and End Results (SEER) 13 Database. Of the 228 cases of anorectal melanoma reported, “38.6% occurred in the rectum; 25.4% in the overlapping rectum, anus, and anal canal; 18% in the anus; 17.5% in the anal canal; and 0.5% in the cloacogenic zone,” Dr. Callahan reported.

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White persons aged 75 to 84 years had the highest incidence rates, which were significantly higher among women than men. “This is consistent with prior studies and contrasts with the incidence rates of the more common cutaneous malignant melanomas that are higher among older men than older women.”

From 1992 to 2009, the annual percentage increase in incidence was 6% for men and 4.3% for women (P<0.05). “Future studies should aim to explore this observation further as well as improve early detection of anorectal melanoma in older individuals,” they concluded.

Abstract (search for keyword “Gerstenblith”)