Introduction/Background Management of endometrial cancer consists of surgery followed by tailored adjuvant therapy but there is a risk of pelvic and/or systemic recurrence. Here, we evaluated clinical/pathological features in addition to frequency and site of first relapse in patients with ESGO/ESTRO/ESP High-Intermediate Risk (HIR) endometrioid endometrial cancer who received adjuvant external beam radiotherapy (EBRT) to the pelvis or vaginal brachytherapy (VBT) (± chemotherapy).

Methodology The central radiotherapy prescribing system at our institution was interrogated to identify patients who commenced adjuvant pelvic EBRT (4500cGy/25#) or VBT (2100cGy/3#) for Stage I/II endometrial cancer, 1st January 2017 to 31st December 2019. Risk stratification was performed retrospectively; only those with HIR endometrioid endometrial cancer were included. Clinical follow up was conducted 3–6 monthly until 5 years had elapsed or death occurred (data lock 31st December 2022). Imaging was requested if recurrence was suspected.

Results In total, 173 patients were identified (EBRT, n= 73 and VBT, n=100). Patient demographics and clinical/pathological features are illustrated in table 1. Median follow up was 33 months (range 0–68). By study end, 9/73 (12.3%) patients had relapsed in the EBRT group and 17/100 (17%) in the VBT group. Pattern of relapse consisted of pelvis only (2/9), distant (4/9), and both (3/9) in the EBRT cohort compared with pelvis only (11/17), distant (1/17), and both (5/17) in the VBT cohort. Isolated pelvic relapse, total pelvic relapse, and distant failure rates were 2.7%, 6.8%, and 9.6% following EBRT, and 11%, 16%, and 6% following VBT, respectively.

Conclusion Distant failure rates were lower in the VBT group but isolated and total pelvic failure rates were higher, suggesting that EBRT may be optimal for achieving locoregional control. EBRT is now considered at our institution for HIR endometrioid endometrial cancer in accordance with ESGO/ESTRO/ESP 2020 guidelines, especially in the absence of lymph node staging.

Disclosures None