R. A. Patel1, P. D. Patel1, K. Ashack1, D. C. Wan2 1University Of Illinois At Chicago,College Of Medicine,Chicago, IL, USA 2Stanford University,Plastic And Reconstructive Surgery,Palo Alto, CA, USA
Introduction: The role of sentinel lymph node biopsy (SLNB) in melanoma is highly controversial topic. Current data is primarily drawn from the MSLT-1 Trial. Although results showed no overall survival benefit, SLNB provided a disease-free survival benefit for intermediate thickness (1.2-3.5mm) and thick (>3.5mm) melanoma. In the perineum, melanoma is often more advanced at presentation, with current guidelines primarily translated from melanoma in a non-anatomic specific fashion. As a result, the role of SLNB in this anatomic region is even more poorly understood.
Methods: The Surveillance, Epidemiology, and End Results (SEER) program is a large population-based cancer registry including survival data from millions of patients in the United States. The registry was used to generate patient data for analysis from 2004-2015. Inclusion criteria included melanoma of the vulva, penis, and scrotum; Breslow depth >0.80mm with ulceration and >1.00mm with any features; and nodal intervention of SLNB with associated lymph node dissection if performed, or none. A χ2 analysis was performed to determine predictors of sentinel node status. Kaplan-Meier regression analysis was performed for SLNB stratified by Breslow depth. Subsequently a multivariate cox proportional hazards regression was performed to determine predictors of disease-specific survival (DSS) and overall survival (OS).
Results: Aggregates for disease-specific and overall survival was improved with implementation of SLNB. 5-year survival rates with SLNB were 52.9% and 49.6%, as compared to those without SLNB at 32.5% and 32.5% for DSS (p = 0.001) and OS (p <0.001) respectively. Patients with positive node status had a 5-year DSS and OS of 24.1% and 22.3% respectively, compared to 63.8% DSS and 60.2% OS for a negative node status (p <0.001 and p <0.001). Stratification by Breslow depth yielded significant OS advantage for the 0.80-2.00mm group (33.7% benefit; p = 0.001). Significant predictors of survival (DSS; OS) include age greater than 75 (HR 2.108, p = 0.030; HR 2.136, p = 0.010), Clark level IV-V (HR 2.474, p = 0.035; HR 2.05, p = 0.035), and positive ulceration status (HR 1.946, p = 0.011; HR 1.941 p = 0.003). High mitotic rate (HR 1.865, p = 0.053) was a predictor for poor OS only.
Conclusion: SLNB may be offered to patients with melanoma of the perineum with Breslow depth >0.80mm with ulceration up to 2.00mm, or any lesions >1.00mm up to 2.00mm for prognostic information as well as therapeutic benefit through an increase in 5-year overall survival. Additional randomized controlled trials are necessary before more definitive conclusions are made.
