Impact of adjuvant therapies following surgery for anal melanoma

Background Anal melanoma is rare. Surgery is standard of care for non-metastatic disease. There are limited data supporting adjuvant therapy. We sought to examine the impact of adjuvant radiation, chemotherapy and immunotherapy on survival. Methods The National Cancer Database was queried. Factors associated with overall survival were examined by Kaplan-Meier and Cox proportional hazards analyses. Patients were grouped by treatment regimen. Results 450 patients had complete treatment data: surgery alone (63.8%), surgery + radiation (14.9%), surgery + chemotherapy (7.6%), surgery + immunotherapy (9.6%) and non-surgical treatment (4.2%). Median survival was 27.2 months. Node-positive patients had worse survival than node-negative (22.4 vs. 36.8 months; p = 0.0002). Non-surgical treatment yielded worse survival than any surgery-inclusive regimen (10.4 vs. 27.8 months; p = 0.0002). No adjuvant modality conferred a survival advantage. By multivariate analysis, increasing age (HR/1 year = 1.02, p = 0.012) and node positivity (HR = 2.10, p = 0.0002) negatively impacted survival. Conclusion Adjuvant therapy for non-metastatic anal melanoma does not appear to influence survival.