Objective: The aim of this study was to determine the significant prognostic factors for primary anorectal melanoma and propose a standard surgical procedure.
Patients and methods: From 1975 to 1995, 19 patients with primary melanoma of the anus were treated. Five patients were given palliative care, 6 had abdominoperineal amputation and 8 had curative local transrectal tumoral excision. Two patients also underwent inguinal node dissection.
Results: Overall 5-year survival was 21%. Univariate analysis showed a significantly poorer prognosis when: inguinal or pelvic nodes were invaded (p = 0.01), surgical margins were invaded (p = 0.003), visceral metastases were present (p = 0.01) and the tumor measured over 20 mm thick (p = 0.01). Prognosis was unchanged by the type of surgical exeresis.
Conclusions: Local transrectal excision is the first ling choice for primary anorectal melanoma. Amputation of the rectum should be reserved for cases where complete tumor resection is technically impossible transrectally. Node dissection is indicated in cases with clinical invasion of the inguinal nodes.