Outcomes of Surgical Treatment for Patients with Anorectal Malignant Melanoma; Results of Nine Cases in a Single Institution.

Anorectal melanoma (AM) is a rare and aggressive malignancy. Two main types of surgical approach for AM are abdominoperineal resection (APR) and wide local excision (WLE). Nine patients with AM underwent surgical treatment between July 2005 and October 2017 at our institution. Two of the patients were diagnosed with localized stage, four with regional stage, and three with distant stage. Laparoscopic APR was performed in six patients with localized and regional stages, whereas palliative APR and/or WLE were performed in those with distant metastasis. Both patients with localized stage lived without relapse for 6.8 years after surgery. One of the patients with regional stage had no relapse during 3.6 years of follow-up. The other three patients had recurrence and died between 6 and 32 months after surgery. The median overall survival (OS) of the cohort was 14.8 months, and the 5- and 10-year OS were 33.3% and 16.7%, respectively. The tumor at the regional stage could be removed through WLE, but preoperative diagnosis of lymph node metastasis is difficult in patients with AM. Further development of the diagnostic method is expected, and future tasks will be to establish the selection criteria to determine which surgical approach is optimal for this devastating disease.