Anorectal melanoma: experience from a tertiary cancer care centre in South India

Introduction Mucosal malignant melanoma of the anorectum is a rare and aggressive disease, in which early diagnosis is difficult. The prognosis remains extremely poor, irrespective of the treatment. We share our experience in treating this malignancy at our centre in South India. Methods This study describes a retrospective analysis of 31 cases of anorectal melanoma presented to our centre between January 2001 and December 2013. Results Twenty-two patients (71%) presented with metastasis and had a median overall survival of nine months. None of the 22 patients survived for two years. Nine patients (29%) had curative surgery, in the form of abdominoperineal resection (six patients), abdominoperineal resection with bilateral inguinal node dissection (one patient), abdominoperineal resection with liver resection (one patient) and posterior exenteration (one patient). In patients who underwent curative surgery, the median overall survival was 15 months and disease-free survival was nine months, with a two-year overall survival of 22%. Conclusions Anorectal melanoma is an aggressive disease with a poor prognosis. The majority of patients present with distant metastases. Prognosis depends on stage at presentation. Early diagnosis and surgical resection may improve the overall outcome. Newer modalities such as immunotherapy and targeted therapies such as anti-CTLA4 monoclonal antibody and anti-programmed cell death protein 1 monoclonal antibodies have radically changed the management of mucosal melanoma and may, in the future, improve the overall prognosis of anorectal melanoma.