Melanoma of the anal canal: a case series.

PURPOSE: Anal melanoma is an uncommon and aggressive cancer. Different surgical modalities have been used in managing the disease with no clear evidence to favor one approach over another.
METHODS: The medical records of patients with anal melanoma treated at the H. Lee Moffitt Cancer and Research Institute between 1987 and 2004 were reviewed. Published anal melanoma studies, including more than ten patients with outcome data, also were reviewed.
RESULTS: Twelve patients were identified (8 percent of all cancer of the anal canal). Nine were females with a median age of 67 (range, 27-86) years. Four patients had nodal involvement, and one had bone metastases at the time of diagnosis. Five patients had abdominoperineal resection, and six had local excision. Adjuvant radiation therapy with or without interferon was used. Five of the 11 patients without metastatic disease relapsed or died within the first year of diagnosis (4 had local excision and 1 had abdominoperineal resection). Median time to relapse was 6.5 (range, 4-31) months. The liver was the most common site for relapse. Only one patient treated with local excision followed by interferon was a long survivor (no evidence of recurrence at 54 months).
CONCLUSIONS: Anorectal melanoma is a rare and challenging disease. The preoperative staging influences the treatment schedule. In the absence of strong survival benefit of abdominoperineal resection in managing the nonmetastatic form of the disease, it is reasonable to consider local excision as the initial treatment of choice. Adjuvant radiation therapy is well tolerated and is promising in improving locoregional control.