A. T. Hawkins1, T. Geiger1, R. Muldoon1, B. Hopkins1, M. Ford1 1Vanderbilt University Medical Center,Colon & Rectal Surgery,Nashville, TN, USA
Introduction:
Anal melanoma is a lethal disease but its rarity makes understanding the behavior and effects of intervention challenging. Local resection (LR) and abdominal perineal resection (APR) are the proposed treatments for non-metastatic disease and have each gone in and out of favor over the years. We hypothesize that there will be no difference in overall survival between the two types of resection.
Methods:
The National Cancer Database (NCDB 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 two groups – those who underwent local resection (LR) and those who underwent abdominal perineal resection (APR). Bivariate and multivariable analyses were used to examine the association between resection type and R0 resection rate, short term survival and overall survival.
Results:
570 patients with anal melanoma who underwent resection were identified over the study period. The median age was 68 and 59% of patients were female. 383 (67%) underwent LR. Rate of LR did not change significantly by year. Factors associated with the use of LR included older age, government insurance, and treatment at a high volume center. LR was associated with lower rates of R0 resection rates (LR 73% vs. APR 91%; p<0.001). Overall five year survival for the entire cohort was 20%. There was no significant difference in five-year overall survival (LR 17% vs. APR 21%; p=0.31). (SEE FIGURE) Even when adjusting for confounding variables including age, gender, comorbidity, and R0 resection in a Cox proportional hazard multivariable model there was no significant survival difference between resection methods (OR 0.84; 95%CI 0.66-1.06; p=0.15). In addition, there was no improvement in overall survival for patients who underwent R0 resection (OR 1.18; 95%CI 0.90-1.56; p=0.22).
Conclusion:
Anal melanoma has an abysmal prognosis, with only 1 out of 5 patients alive at five years. Older age, government insurance, and treatment at a high volume center were associated with local resection. 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. Given the known morbidity of APR resection, local resection should be considered in cases of anal melanoma.
Figure- Kaplan-Meier Curve for Overall Survival Comparing Method of Resection
