Cutaneous Genital and Acral Melanoma Treatment Trends and Outcomes

Wide local excision (WLE) removes clinical tumor and adjacent skin (‘tumor margin’). After defect repair, tissue is evaluated microscopically. Re-excision occurs if tumor remain. Mohs Micrographic Surgery (MMS) removes clinical and microscopic tumor before defect repair. While recurrence, positive margin, and upstaging (increase in tumor’s stage after diagnostic biopsy) rates for trunk and proximal extremity melanoma WLE are 2%, for ‘specialty site’ (acral and genital) cutaneous melanomas these rates each increase to 10%. Before 2020, the National Comprehensive Cancer Network guidelines recommended WLE for melanoma. In 2020 they included the option of MMS for early-stage specialty site cutaneous melanomas due to their cosmetic, functional, and anatomically-constrained nature. Single-center studies demonstrate 0.5%-1% and 10% recurrence rates for MMS and WLE-treated specialty site cutaneous melanomas, respectively. However, multicentered, larger studies on specialty site, especially genital and acral (palm, sole, and nail) melanomas, are lacking.
Objectives: Utilize Surveillance, Epidemiology, and End Results (SEER)-Medicare to evaluate national rates and outcomes of WLE and MMS for specialty site cutaneous melanomas over the last 20 years. Outcomes include mortality, melanoma specific survival, and recurrence rates. Associations between immune-status, race, income, gender, education and surgical treatment (WLE and MMS) will be studied to determine if disparities exist.

Methods: Kaplan Meier statistics and Joinpoint analysis will analyze recurrence and trends over time, respectively. Multivariable logistic regression will evaluate associations between demographic factors and surgical management (MMS vs WLE).

Significance: This nationwide evaluation of specialty site cutaneous melanoma surgical trends and outcomes can impact melanoma guidelines, optimize patient care, and identify treatment disparities.