Anorectal malignant melanoma: retrospective analysis of management and outcome in a single Portuguese Institution

Anorectal melanoma is an uncommon cancer with a poor prognosis. We aim to describe the clinical presentation, treatment and outcome of patients with anorectal melanoma in our center. Retrospective study of patients with anorectal melanoma treated between 2000 and 2011 at a cancer center in Lisbon. Ten patients were identified, eight females and two males, with median age 70.5 years (32–79). Symptoms at presentation were rectal bleeding (8), anal pain (4) and discomfort (3). Tumor location was anal (6), rectal (3) and anorectal transition (2). Seven patients had surgery: abdomino-pelvic resection (5) and local resection (2). Among the two patients who underwent local resection, one was an incidental finding in a hemorrhoidectomy specimen. This patient had further adjuvant chemotherapy (dacarbazine). Three patients had distant metastasis at diagnosis, one had chemotherapy and two had best supportive care. Six of the seven operated patients relapsed in a median time of 5.4 months: distant metastasis (4), local recurrence (1), both (1). The two local relapse patients had surgical widening of resection margins (1) and radiotherapy (2). One-year survival was 30 %; 3-year survival was 20 %. Anorectal melanoma has a poor prognosis due to advanced disease at presentation and aggressive course, with relapse in almost all operated patients. Treatment guidelines have not been established due to the lack of randomized studies. However, recent studies show that sphincter-sparing surgical procedures along with low dose intensity radiotherapy seem to achieve a local control similar to abdomino-pelvic resection. No systemic therapy is considered standard of care for advanced disease, and regimens are extrapolated from cutaneous melanoma experience.