Clinical outcomes and prognostic factors of adjuvant radiotherapy for vulvar cancer: a Japanese Gynecologic Oncology Group nationwide survey study

This study aimed to analyze the clinical outcomes and prognostic factors of postoperative adjuvant radiotherapy (RT) for vulvar cancer based on a retrospective Japanese nationwide survey. Data were collected from 108 institutions for patients diagnosed with vulvar cancer between January 2001 and December 2010. Patients with histologically confirmed squamous cell carcinoma, adenocarcinoma, or adenosquamous carcinoma who underwent curative surgery and adjuvant radiotherapy were included in this study. Survival outcomes were estimated using the Kaplan-Meier method, and prognostic factors were analyzed via univariate and multivariate models. A total of 139 patients were included, with a median follow-up of 44 months (range: 3-169). The 5-year overall survival (OS) rates (95% confidence interval [CI]) for stages I, II, III, and IV were 71.8% (50.8-92.8%), 61.3% (40.1-82.5%), 58.0% (45.8-70.2%), and 47.3% (27.5-67.1%), respectively. The corresponding 5-year cause-specific survival (CSS) rates (95% CI) for stages I, II, III, and IV were 71.8% (50.8-92.8%), 73.4% (53.0-93.8%), 62.2% (50.0-74.4%), and 47.3% (27.5-67.1%). Multivariate analysis identified age ≥70 years as an independent adverse prognostic factor for OS (hazard ratio [HR]: 1.848; 95% CI: 1.039-3.281; P = 0.042), while the presence of ≥2 inguinofemoral lymph node metastases was significantly associated with poorer CSS (HR: 2.179; 95% CI: 1.109-4.280; P = 0.030). Our analysis identified advanced age and a higher nodal burden as significant predictors of poorer survival outcomes in patients with vulvar cancer receiving postoperative adjuvant RT.