Objective To investigate the utilization and outcomes of adjuvant immunotherapy for patients with vulvar melanoma and inguinal lymph node metastases.

Methods The National Cancer Database was accessed and patients with vulvar melanoma diagnosed between 2004 and 2015 who did not have distant metastases, underwent inguinal lymphadenectomy, had positive lymph nodes, and at least 1 month of follow-up were identified. Administration of immunotherapy was evaluated and clinicopathological characteristics were compared. Median overall survival was compared with the log-rank test. Stratified analysis based on clinical status of lymph nodes was performed. A Cox model was constructed to evaluate survival after controlling for confounders.

Results A total of 300 patients were identified; the rate of immunotherapy use was 25% (75 patients). Patients who received immunotherapy were younger (median 58 vs 70 years, p<0.001); however, the two groups were comparable in terms of clinical lymph node status, rate of positive tumor margins, presence of tumor ulceration, tumor size, Breslow thickness, and performance of comprehensive lymphadenectomy. There was no overall survival difference between patients who did (median 31.08 months) and did not (median 22.77 months) receive immunotherapy (p=0.18). Following stratification by clinical lymph node status, immunotherapy did not improve overall survival of patients with clinically negative (median 35.35 vs 33.22, p=0.75) or positive lymph nodes (median 23.33 vs 16.99, p=0.64). After controlling for confounders, administration of immunotherapy was not associated with better overall survival (HR 0.81, 95% CI 0.57 to 1.14).

Conclusions In this study approximately one in four patients received adjuvant immunotherapy. Immunotherapy was not associated with improved overall survival.