Dose-escalated intensity modulated radiation therapy in patients with locally-advanced vulvar cancer - does it increase response rate?

GOG 205 safely increased clinical (cCR) and pathologic complete response (pCR) in locally-advanced vulvar cancer through dose escalation using three-dimensional radiotherapy (RT). The aim of this study is to assess the response of dose-escalated intensity modulated radiotherapy (IMRT) in locally-advanced vulvar cancer. A retrospective review of patients treated with dose-escalated (≥ 55Gy) IMRT from 2012 to 2018 for locally-advanced vulvar cancer was performed. Patients treated with preoperative or definitive intent were included. Rates of cCR and pCR were assessed, and predictors of disease-free survival (DFS) were analyzed using the Kaplan Meier method with log rank test between groups and a parsimonious multivariate Cox model. Median dose to the vulva was 66.0 Gy (Interquartile Range [IQR]: 66.0–68.0) for definitive and 59.4 Gy (IQR: 58.0–59.4) for preoperative IMRT. The overall rates of cCR and pCR were 76% and 70%, respectively. DFS at two years was 65% (95% Confidence Interval [CI] 50–80%) for all patients, 81% (95% CI 63% - 98%) for definitive IMRT, and 55% (95% CI 35% - 76%) for preoperative IMRT. On multivariate analysis, cCR predicted for disease-free survival (HR 0.21; 95% CI 0.06–0.76; p = 0.02), and pCR predicted for OS (HR 0.12; 95% CI 0.02–0.60; p = 0.01). Grade 3 acute and late RT toxicity was seen in 14 (29%) and 3 (6%) of patients, respectively. Dose-escalated IMRT for locally-advanced vulvar cancer is well tolerated, with rates of cCR and pCR that compare favorably with published data. •Median dose to the vulva was 66.0 Gy for definitive and 59.4 Gy for preoperative IMRT.•The rates of cCR and pCR were 48% and 31% in GOG 101, 64% and 50% in GOG 205, and 76% and 70% in the present study.•Patients node negative on imaging received 45–50 Gy to the groin without biopsy.•No isolated inguinal failures were observed in patients that were node negative on imaging.•On multivariate analysis, cCR predicted for disease-free survival and pCR predicted for OS.