Anorectal malignant melanoma: treatment with surgery or radiation therapy, or both

Anorectal malignant tumours are increasing in frequency for unknown reasons. Surgery is the principal treatment, and the role of adjuvant therapy has not been defined. We therefore decided to review the experience of the Princess Margaret Hospital in Toronto, a large tertiary care cancer hospital, with respect to the surgical management of anorectal melanoma.

We reviewed the charts of all registered patients with anorectal malignant melanoma (AMM) treated with surgery or radiotherapy, or both, at the hospital between 1980 and 1999, paying particular attention to survival, and local and distant recurrences.

There were 14 patients, all of whom were followed up to the time of death or for a minimum of 28 months for surviving patients. The mean ages at diagnosis were 56 years for men and 68 years for women. Clinical staging was as follows: local, 10 patients; locoregional, 3 patients and metastatic disease, 1 patient. Local therapy included local resection alone in 7 cases and abdominoperineal resection in 7. Seven patients received pelvic irradiation at some time during their disease, using different doses and fractionation schemes. Three of them had concomitant chemotherapy and radiotherapy with no tumour regression. In all 3 patients the lesions was reclassified as AMM and the patient underwent surgery. The other 4 patients had a short course of radiotherapy for palliation after the original lesion recurred. The overall median survival was 12 (range from 3-51) months. Two patients remained alive at last follow-up. Patients managed by local excision had a median survival of 12 (range from 3-51) months, and those managed by abdominoperineal resection had a median survival of 7 (range 5-51) months. Of the 10 patients treated initially with local excision, 6 required reoperation. Three underwent salvage abdominoperineal resection. Six patients were alive 1 year after treatment (median survival 32.5 mo [range from 21-51 mo]). Eight patients had a rapid evolution of their disease with a median survival of 5.5 (range from 3-12) months. Eleven of the 12 patients who died had metastatic disease.

Systemic dissemination is almost universal in patients with AMM. The overall survival was poor regardless of local treatment. There was a 60% failure rate of local excision, which necessitated further surgery. Improving local control is important since some patients will survive up to 3 years.