Comparison of Survival Outcomes Between Local Excision and Radical Resection in Patients With Anorectal Malignant Melanoma

Background: Anorectal malignant melanoma (ARMM) is a rare but highly aggressive malignancy with poor prognosis. Due to its rarity, the optimal surgical approach (local excision [LE] vs. radical resection [RR]) remains controversial. While RR aims to achieve wider margins and lymph node dissection, LE offers advantages in reduced morbidity and better functional preservation. This SEER-based study comparatively evaluated long-term survival outcomes between LE and RR in ARMM patients. Methods: Clinicopathological data of patients with ARMM were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. A 1:1 propensity score matching (PSM) approach was employed to balance baseline covariates between the surgical groups (P < 0.05). Cox proportional hazards models were used to identify risk factors for cancer-specific survival (CSS) and overall survival (OS). Results: Among 196 eligible patients, those in the RR group were older and more likely to present with advanced N-stage disease. Both pre- and post-PSM analyses showed no survival advantage of RR over LE. Multivariate analysis identified diagnosis during 2009–2017, N2 stage, and M1 stage as independent predictors of poorer CSS. For OS, N2 stage and omission of postoperative radiotherapy were independently associated with worse outcomes. Conclusion: Radical resection does not confer a survival benefit over local excision in the treatment of ARMM. LE may be the preferred surgical approach, offering an optimal balance between oncological efficacy and functional preservation.