Prognostic Determinants of Salvage Image-Guided Brachytherapy for Vaginal Recurrence of Endometrial Cancer

Abstract

In PORTEC-1, the 5-year survival after vaginal relapse from early stage endometrial cancer was 65% for patients in the observation arm. In this study, we evaluated clinical outcomes and toxicity in patients with vaginal relapse of endometrial cancer treated with salvage image-guided brachytherapy (BT). Retrospective review identified 62 patients with early stage endometrial cancer and biopsy-proven vaginal recurrence treated with external beam (EBRT) and image-guided BT with definitive intent between 10/04 and 05/17. All patients had prior hysterectomy without adjuvant radiotherapy (RT) and >3 months follow-up (FU). Rates of vaginal control (VC), recurrence-free survival (RFS) and overall survival (OS) were estimated by Kaplan-Meier method. Univariate analysis was performed by Cox proportional hazards or log-rank test. Late toxicity was graded by CTCAE. Median FU was 31.8 months (r: 3.2 – 160.5). Baseline characteristics are summarized in table 1. The median time to recurrence after hysterectomy was 18.2 months (range [r]: 1.6 – 158). Median tumor size was 2.3 cm (r: 0.3-7.5). Median prescribed dose and HR-CTV D90 in EQD2 were 75.4 Gy and 75.3 Gy, respectively. Twenty patients had disease relapse at a median of 14.2 months after completion of BT (6 with vaginal failure only, 2 vaginal and distant, and 12 distant only). The 3-year rates of VC, RFS, and OS were 86%, 70% and 80%. respectively. Tumor grade at hysterectomy was a strong determinant of outcome, with 3-year RFS rates of 80% for grade 1 tumors, 78% for grade 2, and 13% for grade 3 (p<0.01). Age, stage at diagnosis, nodal involvement and BT modality were not associated with RFS (all p>0.2). Median HR-CTV D90 was 75.7 Gy for patients with vaginal failure and 75.2 Gy for those without (p=0.9). Age, BT modality, tumor grade, tumor size and cumulative prescribed dose were not prognostic for VC (all p>0.5). Late grade 3 toxicity included 2 patients with proctitis and 1 with urinary incontinence; all received interstitial BT. One cylinder patient had grade 3 vaginal stenosis. Salvage RT with image-guided BT results in excellent clinical outcomes for patients with grade 1 or 2 tumors and vaginal relapse. Those with grade 3 tumors or non-endometrioid histologies have high rates of distant recurrence and poor survival. Adjuvant treatment should be considered for all high risk patients given the low rates of salvage.Abstract 2796; Table 1Baseline characteristics for 62 patientsn (%)FIGO 2009 stage at diagnosis • IA• 56 (90%) • IB• 5 (8%) • II• 1 (2%)Histology • Endometrioid• 55 (89%) • Serous• 5 (8%) • Carcinosarcoma• 2 (3%)Grade • 1• 40 (65%) • 2• 13 (21%) • 3• 9 (14%)Median age at recurrence67 years (r: 41-86)Site(s) of recurrence • Vaginal only• 55 (89%) • Vaginal + nodal• 7 (11%)Image-guided BT modality • Intracavitary (cylinder)• 26 (42%) • Interstitial• 36 (58%)Median central EBRT dose• 45Gy (r: 44 – 54)Median BT dose• 25Gy (r: 16 – 35)Median D2cc OAR • Bladder• 65.8 Gy (r: 50.7 – 87.2) • Rectum• 64.7 Gy (r: 52.1 – 86.9) • Sigmoid• 53.7 Gy (r: 44.7 – 75.5)Chemotherapy use11 (18%) Open table in a new tab