Role of immunotherapy for lymph-node positive vulvar melanoma: Utilization and outcomes (154)

Abstract

<b>Objectives:</b> To investigate the utilization and outcomes of immunotherapy in the management of patients with inguinal lymph node-positive vulvar melanoma using a large hospital-based database. <b>Methods:</b> Patients with vulvar melanoma diagnosed between 2004 and 2015 who did not have distant metastases, underwent inguinal lymphadenectomy, had positive lymph nodes per pathology report, and had at least one month of follow-up were selected from the National Cancer Database. Administration of immunotherapy was evaluated, and clinical-pathologic characteristics were compared with the Chi-square test. Median overall survival (OS) was determined following the generation of Kaplan-Meier curves and compared with the log-rank test. Stratified analysis based on the clinical status of lymph nodes was performed. A Cox model was constructed to evaluate survival after controlling for a priori selected confounders. <b>Results:</b> A total of 300 patients were identified; the rate of immunotherapy use was 25% (75 patients). In the present cohort, chemotherapy (9.3%, 28 cases) and radiation therapy (15%, 45 cases) were rarely employed. Patients who received immunotherapy were younger (median 58 vs 70 years, p<0.001) and more likely to have private insurance (53.3% vs 35.1%, p=0.018). The two groups were comparable in terms of clinical LN status, rate of positive tumor margins, rate of comprehensive LND (defined as >10 LN removed), presence of tumor ulceration, tumor size, and Breslow thickness. There was no OS difference between patients who did (median OS: 31.08 months) and did not (median OS: 22.77 months) receive immunotherapy (p=0.18). In addition, there was no OS difference between patients who had limited (median: 22.51 months) or comprehensive LND (median: 27.01 months) (p=0.26). Following stratification by clinical LN status, immunotherapy did not improve OS for patients with clinically negative LNs (median OS: 35.35 vs 33.22, p=0.75) or clinically positive LNs (median OS: 23.33 vs 16.99, p=0.64). After controlling for tumor size, Breslow thickness, clinical lymph node status, history of another tumor, insurance status, presence of medical comorbid conditions, and the number of lymph nodes removed, administration of immunotherapy was not associated with better OS (HR: 0.81, 95% CI: 0.57, 1.14). <b>Conclusions:</b> Approximately one in four patients with vulvar melanoma and lymph node metastases will receive immunotherapy with no clear survival benefit. Comprehensive lymphadenectomy does not confer a survival benefit in this patient cohort. Further research is warranted to identify novel treatment options for patients with this rare disease.