Survival trends and subsite variation in mucosal melanoma: A SEER database analysis.

Abstract

e21606 Background: Mucosal melanomas are rare neoplasms, representing approximately 2% of all melanoma cases. They often present at more advanced stages, and carcinogenesis is poorly understood. This study aimed to characterize current survival trends in mucosal melanoma across primary subsites and compare outcomes with its cutaneous counterpart using the Surveillance, Epidemiology, and End Results (SEER) Database. Methods: SEER Research Plus Data (17 Registries, 2000-2022) was used to extract all melanoma cases with ICD codes 8720-8790. Mucosal cases were subdivided into oral/pharyngeal (OP), airway/sinonasal (AS), gastrointestinal (GI), genitourinary (GU), renal/urinary, and lacrimal sites using ICD-O-3 primary site codes. Overall survival (OS) was estimated using Kaplan-Meier methods and compared using the log-rank test. Multivariable Cox models estimated hazard ratios HR) for OS, adjusting for age, sex, race, diagnostic era, and SEER summary stage. Results: Among 464,736 melanoma tumor cases, 447,387 were cutaneous and 4,910 were mucosal. Median age at diagnosis was 70-74 years. Mucosal melanoma was most common in Caucasians (73.5%), followed by Hispanic (12.2%), Asian (8.0%), Black (5.3%), and American Indian/Alaska Native (0.7%) patients. GU sites comprised 39% of mucosal cases, followed by AS (26.8%), GI (24.0%), and OP sites (7.8%). Renal/urinary and lacrimal primaries were rare ( < 3%). In unadjusted analyses, median OS was shorter for mucosal compared with cutaneous melanoma (24 vs 240 months; log-rank p < 0.001). After adjustment, mucosal melanoma remained independently associated with worse OS compared with cutaneous melanoma (HR 2.33, 95% CI 2.21-2.45; p < 0.001). Comparing mucosal sites, GU had the longest median OS (36 months; 95% CI 31-41), followed by OP (28; 95% CI 22-39), AS (21; 95% CI 19-24), and GI (16; 95% CI 15-18). In multivariable analysis, GI were independently associated with worse OS compared with OP (HR 1.35; 95% CI 1.17-1.56), while AS and GU were not significantly different. Conclusions: This analysis reaffirms the rarity of mucosal melanoma and highlights its markedly poorer prognosis compared with cutaneous melanoma. Survival differed significantly by primary subsite, with GU and OP primaries demonstrating the most favorable outcomes and GI primaries the poorest. Despite its rarity, persistently poor survival underscores the need for further investigation into mucosal melanoma pathogenesis and site-specific treatment strategies. Overall survival by primary mucosal melanoma subsite. Group / Subsite N patients Median OS, months (95% CI) 5-year OS, % (95% CI) Cutaneous melanoma 447,387 240 (238-242) 80.0 (79.8-80.1) Mucosal melanoma (overall) 4,910 24 (23-26) 29.9 (28.4-31.4) Oral/Pharyngeal 416 28 (22-39) 31.7 (26.7-37.7) Airway/Sinonasal 1296 21 (19-24) 25.9 (23.3-28.7) Gastrointestinal 1172 16 (15-18) 18.8 (16.4-21.6) Genitourinary 1909 36 (31-41) 39.0 (36.6-41.6)