Salvage interstitial brachytherapy for treatment of recurrent endometrial cancers in the vagina: Seven-year single institution experience and review of second recurrence patterns

Interstitial brachytherapy (ISBT) is a known treatment for vaginal recurrence of endometrial cancer. This study reviews a large tertiary institution's ISBT experience and outcomes for vaginal recurrences. Patients who underwent salvage ISBT for vaginal recurrence of endometrial cancer from January 1, 2014 to August 31, 2021, were identified. Initial and salvage disease factors and treatments were recorded. Outcomes were calculated including overall survival, local, and distant failure. Thirty-nine patients were included; thirty received external beam radiotherapy and interstitial brachytherapy (EBRT + ISBT) while 9 received ISBT alone. At initial diagnosis, the ISBT alone group had an older median age, with stage IA-IV disease, frequently receiving adjuvant treatment, compared to the EBRT with ISBT group with mainly stage IA disease who did not. Median follow up was 22 months and median time to recurrence 14 months (16.5 months in EBRT + ISBT group and 14 in the ISBT alone group). Two-year overall survival was 85% for all patients, 85.6% and 83.3%in the EBRT + ISBT and ISBT alone groups, respectively. Local failure was 22.7% for all patients, 16.7% in the EBRT + ISBT group and 11.1% in the ISBT alone group. Median HRCTV D90 (EQD2) was 76.8 Gy in the EBRT + ISBT group, and 57.9 Gy in the ISBT alone group. Late grade 3 or higher toxicity occurred in only 3 patients. EBRT + ISBT is an effective treatment for endometrial cancer vaginal recurrence, with acceptable toxicity. ISBT alone is an option for patients with contraindications to or with previous treatment of pelvic radiation.