Introduction/Background Stage III endometrial cancer is managed with surgery and adjuvant chemoradiotherapy. The optimal treatment for Stage I/II high risk disease remains controversial. Here, we evaluated frequency and site of first relapse following adjuvant vaginal brachytherapy for FIGO Stage I-II endometrial cancer with non-endometrioid histology.

Methodology The central radiotherapy prescribing system at our institution was interrogated to identify patients who commenced vaginal brachytherapy, 2100cGy/3#, for endometrial cancer, 1st January 2017 to 31st December 2019. Only those with Stage I-II disease and non-endometrioid pathology were included. Clinical follow up was undertaken until death or 5 years had elapsed (data lock 31st December 2022).

Results In total, 68 patients were identified. Median age was 69 years (range 47–92) and median follow up was 33 months . FIGO 2018 Stage: IA (54.4%); IB (20.6%); II (25%). Pathology: serous (60%); carcinosarcoma (22%); clear cell (12%); undifferentiated/mixed (6%). Pelvic lymph node dissection (PLND) was performed in 50/68 (74%) and lymphovascular invasion (LVSI) was present in 25/68 (37%). Adjuvant chemotherapy (Carboplatin AUC5/Paclitaxel 175mg/m2) was delivered to 11/68 (16%) patients; median number of cycles - 4 (range 2–6). By study end, 23/68 (34%) patients had relapsed and 17/68 (25%) had died. Relapse frequency based on clinical/pathological characteristics: pathology (serous - 16/23, other - 9/23), stage (IA/B - 11/23, II - 12/23), LVSI (yes - 13/23, no – 10/23), PLND (yes – 17/23, no – 6/23), chemotherapy (yes – 5, no – 18).Pattern of relapse: pelvis only - 6/23 (26%), distant only - 4/23 (17%), both pelvis and distant – 13/23 (57%). Overall pelvic failure rate was 19/68 (28%).

Conclusion Pelvic recurrence rate was almost 30% despite adequate nodal staging and negative LVSI in >60% of cases. External beam radiotherapy should be strongly considered in early stage non-endometrioid pathology to improve loco-regional control.

Disclosures None