High-dose-rate interstitial brachytherapy for vaginal endometrial cancer recurrence after prior surgery and radiotherapy.

Abstract Purpose Characterize the clinical outcomes of endometrial cancer vaginal recurrences after previous surgery and radiation therapy treated with reirradiation including image-guided interstitial high-dose-rate (HDR) brachytherapy. Methods and materials A single-institution retrospective study identifying women receiving reirradiation for vaginal recurrence of endometrial cancer between 2004 and 2017. Results Twenty-three women had vaginal recurrences of endometrial cancer, median 13.7 months (range 3.5–104.9) from initial radiation. All received reirradiation with interstitial HDR brachytherapy, and seven also received external beam radiation. Median reirradiation EQD2_10 was 48 Gy (range 24.0–68.81), and median cumulative EQD2_10 was 106.25 Gy (range 62.26–122.0). Median follow-up after reirradiation was 40.2 months (range 4.5–112.7). At 3 years, overall survival was 56%, cancer-specific survival was 61%, and disease-free survival was 46%. 14 patients experienced disease recurrence; 10 including distant sites, one at a regional node only. Three patients experienced local recurrences, two of whom did not complete the prescribed course of reirradiation. The overall crude local control rate was 87%. Three patients experienced Grade 3 vaginal toxicity. There was no bladder or rectal toxicity with Grade >2. Conclusions Reirradiation including interstitial HDR brachytherapy is a promising option for vaginal recurrences of endometrial cancer after prior radiation, with high rate of local control and acceptable toxicity. However, distant failure is common. Further studies are needed to determine cumulative radiation dose limits and the role of systemic therapy in this scenario.