3771 - What is the Value of Concurrent Chemoradiation for Vaginal Recurrence of Endometrial Cancer in the Setting of Prior Brachytherapy?
Presenter(s)
C. S. Medina1, A. Groszkiewicz2, J. Lesnock3, P. Sukumvanich3, M. Boisen3, M. B. Courtney-Brooks3, J. L. Berger3, S. Taylor3, A. Olawaiye3, A. Garrett3, S. Rush3, B. P. Venkatesulu4, P. N. Barry4, C. J. Houser2, M. Hajduk2, M. diMayorca5, E. Doraisamy2, H. Kim2, and J. A. A. Vargo IV2; 1University of Pittsburgh School of Medicine, Pittsburgh, PA, 2Department of Radiation Oncology, University of Pittsburgh Medical Center, Pittsburgh, PA, 3Department of Gynecologic Oncology, University of Pittsburgh Medical Center, Pittsburgh, PA, 4Department of Radiation Oncology, UPMC Hillman Cancer Center, Pittsburgh, PA, 5Department of Radiation Oncology, University of Pittsburgh School of Medicine, Pittsburgh, PA
Purpose/Objective(s): GOG0238 demonstrated no benefit to concurrent cisplatin with salvage radiotherapy for vaginal recurrence of endometrial cancer, however patients with prior radiotherapy were excluded. Dose-escalation for recurrent endometrial cancer following prior vaginal brachytherapy is challenged by cumulative doses to organs at risk (OAR), and thus it remains unclear if concurrent cisplatin in the re-irradiation setting would improve outcomes. We hypothesize that despite dose reduction to respect cumulative dose to OARs, concurrent cisplatin with salvage re-irradiation does not improve outcomes.
Materials/Methods: Retrospective review of 22 patients with vaginal recurrence of endometrial cancer receiving salvage external beam radiotherapy (EBRT) and brachytherapy ± cisplatin following previous irradiation with vaginal brachytherapy from 2018-2025. Prior to GOG0238, concurrent chemoradiation was institutional preference for patients without contraindication. After GOG0238, concurrent chemotherapy was no longer recommended for salvage treatment. Patients received EBRT with reduced dose of 30.6 Gy in 17 fractions and sequential boost to pelvic nodes to 45Gy in 25 fractions followed by brachytherapy with 22.5-30 Gy across 5-6 fractions. Cumulative D2cc (EQD2) was limited to <90Gy to bladder and <75 Gy to rectum and sigmoid with no discounting from prior radiation, and the cumulative EQD2 goal for HR-CTV D90 was >60 Gy.
Results: At median follow-up of 40.9 months (IQR: 11.7-83.4), 14 (64%) patients received salvage radiation alone and 8 (36%) received 40 mg/m² concurrent cisplatin across 5-6 cycles. The median HRCTV D90 was 67.7 Gy for all patients, 67.4 Gy for radiotherapy (RT) alone, and 69.9 Gy for chemoradiotherapy (CRT). The median HRCTV was 26.86 cc for all patients (IQR: 20.8-30.6), 25.8 cc for RT alone, and 26.9 cc for CRT. The 4-year local control was 72% (95% CI 51-93%). There was no significant difference in local control for RT alone versus CRT (4-year local control 58% vs. 88%, p=0.23) nor overall survival (4-year overall survival 91% vs 100%, p=0.55). There were 2 patients (9%) with grade 3+ late toxicity: 1 (4.5%) grade 3 radiation proctitis and 1 (4.5%) grade 3 necrosis with ureteral stenosis. The overall 4-year rate of grade 3+ toxicity was 12% (95%CI 0-27%); 12% RT alone vs 12% CRT, p=0.87.
Conclusion: Despite the reduced dose to respect organs at risk tolerance, concurrent cisplatin does not appear to improve outcomes for salvage re-irradiation of vaginal recurrences of endometrial cancer after prior surgery and vaginal brachytherapy. The numerical increase in local control without an increase in toxicity associated with CRT combined with low statistical power challenges if there is still a potential role of concurrent chemotherapy with re-irradiation to compensate for the reduced EBRT doses used to respect OAR tolerance.