A national database analysis of the evolution of outcomes of surgery for anal melanoma

Background: This study assessed trends in treatment and outcomes of anal melanomas over a 17-year period. Methods: NCDB was searched for patients with anal melanoma (2004-2020). Receiver-operating characteristic curve analysis was used to determine cutoff year marking increased overall survival (OS) of anal melanoma. Characteristics, treatments, and outcomes in consecutive time periods were compared. Results: A total of 815 patients (mean age: 67.2 years; 59.4% female) were included: 354 in Period 1 (2004-2012) and 461 in Period 2 (2013-2020). Period 2 included fewer abdominoperineal resections (18% vs. 28%, p = 0.002), more local tumor excisions (61.1% vs. 55%, p = 0.002), more often immunotherapy (odds ratio [OR]: 3.41, 95% confidence interval [CI]: 2.22-5.22, p < 0.001) and less often chemotherapy (OR: 0.516, 95% CI: 0.352-0.755, p < 0.001) administered and longer median OS (25.2 vs. 19.8 months, p = 0.006). Independent predictors of worse OS were older age (hazard ratio [HR]: 1.02, p = 0.012), higher Charlson score (HR: 2.32, p = 0.02), and greater number of positive lymph nodes (HR: 1.15, p < 0.001); conversely private insurance (HR: 0.385, p = 0.008) was predictive of increased OS. Conclusions: Anal melanoma patients diagnosed between 2013 and 2020 underwent fewer abdominoperineal resections and more local excisions than patients diagnosed between 2004 and 2013. Increased immunotherapy and longer median OS were noted in period two. Age and private insurance were significant predictors of OS, remaining constant across time periods.