Sentinel Lymph Node Biopsy in Perineal Melanoma: A Surveillance Epidemiology and End Results Program (S.E.E.R.) Study
Ronak A. Patel, BS1, Priyanka D. Patel, BS2, Mimi R. Borrelli, MBBS MSc1, Derrick C. Wan, MD1.
1Stanford University, Stanford, CA, USA, 2University of Illinois at Chicago, Chicago, IL, USA.
PURPOSE: Current management of melanoma focuses on excision with the potential for lymph node evaluation depending on factors such as Breslow depth and ulceration status. The value of sentinel lymph node biopsy (SLNB) is well established in providing prognostic information, as patients with positive sentinel lymph nodes have worse survival outcomes. However, the option to pursue SLNB has not shown to provide any therapeutic benefits in improving survival. Anatomic specific locations for melanoma have been superficially evaluated, and to our knowledge there is no such literature surrounding SLNB in the perineum. Therefore, the purpose of this study is to evaluate the presence of a therapeutic benefit for SLNB and identify risk factors conferring reduced survival in patients with perineal melanoma.
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 ≥0.80mm with or without ulceration; and documented SLNB with associated procedures, or no intervention performed. Outcomes of interest included disease-specific survival (DSS) and overall survival (OS), as well as patient and melanoma characteristics associated with reduced survival.
RESULTS: Aggregates for DSS and OS were improved with implementation of SLNB. 5-year survival rates with SLNB were 54.7% and 49.9%, as compared to those without SLNB (44.9% and 38.0%) for DSS (p = 0.007) and OS (p = 0.001), respectively. Stratification by Breslow depth yielded significant OS advantage for >1.00-2.00mm (17.3% benefit p = 0.033) and >4.00mm (21.2% benefit p = 0.005) Breslow depth (Figure 1). Significant predictors of reduced survival included age greater than 75, Clark level IV-V, Breslow depth >4.00mm, positive ulceration status, melanoma subtype, and high mitotic rate.
CONCLUSION: Although further randomized controlled trials are needed to establish definitive conclusions, our results suggest SLNB and resultant management may provide additional therapeutic benefits for patients with melanoma of the perineum.
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