Sentinel lymph node biopsy utilization in early-stage vulvar cancer: A National Cancer Database Study.
Authors: Bercow Alexandra , Melamed Alexander , Eisenhauer Eric , Bregar Amy , Growdon Whitfield Board , Molina George , Minami Christina Ahn 
Published: June 2022

e17536

Background: Since 2012, sentinel lymph node biopsy (SLNB) has been considered equivalent in terms of survival to standard inguinofemoral lymphadenectomy (IFLD) in patients with early-stage vulvar cancer. Moreover, SLNB is associated with lower rates of postoperative short-term and long-term morbidity. However, uptake of SLNB has been limited and little information exists about factors associated with access to SLNB in vulvar cancer. Methods: Between 2012-2018, women with stage IB vulvar squamous cell carcinoma were identified using the National Cancer Database. Patient, facility, and disease characteristics were compared between patients who underwent SLNB versus IFLD. Multivariable logistic regression analyses, adjusted for patient, facility, and disease characteristics were used to evaluate factors associated with SLNB. Kaplan-Meier survival analysis using log rank test and Cox regression was performed. Results: Of the 3,454 patients, 1,094 (31.6%) did not undergo lymph node evaluation (LNE) and 2,360 (68.3%) underwent LNE, with 1,668 (82.0%) undergoing IFLD and 692 (29.3%) SLNB. On multivariable analysis, patients diagnosed between 2015-2018 were more likely to undergo SLNB than patients diagnosed 2012-2014 (OR 1.86, 95% CI 1.50-2.31). Patients residing in zip codes with the highest proportion of high school graduates were more likely to undergo SLNB than those residing in regions with lower levels of education (OR 2.00, 95% CI 1.28-3.13). Midwestern patients were less likely to undergo SLNB than those in the Northeast (OR 0.70, 95% CI 0.50-0.96). Hospital volume was significantly associated with SLNB rates, with low-volume hospitals defined as those performing 0-8 vulvectomies/year, moderate-volume performing 8-16, and high-volume performing 16-45. Moderate (OR 1.58, 95%CI 1.18-2.09) and high (OR 2.12, 95% CI 1.56-2.88) volume hospitals were associated with higher rates of SLNB compared to low-volume hospitals. Patients with tumors > 3cm in size were less likely to undergo SLNB than those < 1cm in size (OR 0.69, 95% CI 0.50-0.94). After controlling for patient and tumor characteristics, there was no difference in overall survival (OS) between patients who underwent SLNB and those who underwent IFLD with negative nodes (HR 0.90, 95% CI 0.70-1.15). Similarly, there was no difference in OS between patients who underwent SLNB (with or without subsequent IFLD) and those who underwent IFLD alone with positive nodes (HR 0.99, 95% CI 0.60-1.61). Conclusions: Utilization of SLNB in early-stage vulvar cancer continues to increase over time but significant variation in its use exists at the patient, hospital, and regional level. The lack of survival difference between the two procedures suggests overtreatment in the 71% of node-negative women who underwent IFLD. Further work is needed to de-escalate care that has previously been associated with worse postoperative outcomes in this population.