Resection for anal melanoma: Is there an optimal approach?

Anal melanoma is a lethal disease, but its rarity makes understanding the behavior and effects of intervention challenging. Local resection and abdominal perineal resection are the proposed treatments for nonmetastatic disease. We hypothesize that there is no difference in overall survival between surgical therapies.

The National Cancer Database (2004-2014) was queried for adults with a diagnosis of anal melanoma who underwent curative resection. Patients with metastatic disease were excluded. Patients were divided into 2 groups based on surgical approach (local resection versus abdominal perineal resection). Unadjusted and adjusted analyses were used to examine the association between surgical approach and R0 resection rate, short-term survival, and overall survival.

A total of 570 patients with anal melanoma who underwent resection were identified. The median age was 68 and 59% of patients were female. A total of 383 (67%) underwent local resection. Abdominal perineal resection was associated with higher rates of R0 resection rates (abdominal perineal resection 91% versus local resection 73%; P < .001). Overall 5-year survival for the entire cohort was 20%. There was no significant difference in 5-year overall survival (abdominal perineal resection 21% vs local resection 17%; P = .31). This persisted in a Cox proportional hazard multivariable model (odds ratio 0.84; 95% confidence interval 0.66-1.06; P = .15). Additionally, there was no improvement in overall survival for patients who underwent R0 resection (odds ratio 1.18; 95% confidence interval 0.90-1.56; P = .22).

Anal melanoma has a very poor prognosis, with only 1 of 5 patients alive at 5 years. Although local resection was associated with lower rates of R0 resection, there was no discernable difference in overall survival in both unadjusted and adjusted analysis.