Trends and Outcomes of Sentinel Lymph Node Biopsy in Early-stage Vulvar Squamous Cell Carcinoma: A Population-based Study

Purpose: To compare trends and outcomes between lymphadenectomy and sentinel lymph node biopsy (SLNB) in node-negative early-stage vulvar squamous cell carcinoma (SCC) using a population-based cancer registry. Methods: Patients with vulvar SCC registered on the Surveillance, Epidemiology, and End Results program between 2003 and 2013 were identified. Statistical analysis was performed using Cox regression proportional hazards to calculate hazard ratio (HR) and 95% confidence interval (CI). A 1:1 propensity score matching (PSM) method was performed to minimize selection bias. Results: A total of 1475 patients were identified, including 1346 (91.3%) who received lymphadenectomy and 129 (8.7%) who underwent SLNB. The proportion of patients receiving SLNB increased between 2008 and 2013 compared with the years 2003-2007 (13.9% vs. 3.7%, p < 0.001). Five-year cause-specific survival (CSS) in patients who received lymphadenectomy and SLNB was 91.8% and 92.9%, respectively (p = 0.912), and 5-year overall survival (OS) was 77.5% and 82.5%, respectively (p = 0.403). SLNB was not associated with an decrease in CSS (HR 1.024, 95% CI 0.474-2.213, p = 0.952) or OS (HR 0.874, 95% CI 0.541-1.410, p = 0.581) in univariate and multivariate analyses. A total of 115 pairs were selected by PSM and survival analysis also showed comparable CSS (p = 0.481) and OS (p = 0.545) between lymphadenectomy and SLNB. Conclusions: There is an increasing trend toward SLNB in the treatment of patients with node-negative early-stage vulvar SCC, and survival is comparable between lymphadenectomy and SLNB.