Risk-Based Survival Outcomes in Early-Stage Endometrial Cancer: Impact of Radiation Therapy

Although a new paradigm incorporating molecular and histological classifications has emerged, molecular classification is not routinely performed for all patients in real-world practice. Therefore, evaluating the impact of adjuvant radiation in early-stage endometrial cancer according to risk grouping without molecular classification remains important. This study aims to assess the prognostic impact of adjuvant radiation in intermediate-risk (IR) and high-intermediate-risk (HIR) groups, as defined by the 2021 European Society of Gynaecological Oncology (ESGO) guidelines.

We retrospectively reviewed the medical records of 131 patients with stage I or II endometrial cancer classified as IR or HIR. All patients underwent staging surgery between July 2004 and April 2020 and were followed until December 2023. The prognostic impact of adjuvant radiation on survival outcomes was evaluated using multivariable analysis with a Cox proportional hazards model.

The median age of patients was 59 years, and the median follow-up duration was 73.4 months. Of the 131 patients, 72 (55.0%) were classified as IR and 59 (45.0%) as HIR. Adjuvant radiation was administered to 98 patients, including 45 (62.5%) in the IR group and 53 (89.8%) in the HIR group. Tumor recurrence occurred in 12.5% of IR patients and 8.5% of HIR patients (P = 0.574). In the HIR group, adjuvant radiation was associated with significantly improved progression-free survival (PFS) (P = 0.015). Multivariable analysis further identified older age (> 60 years) and receipt of adjuvant radiation as independent prognostic factors for PFS in the HIR group (P = 0.046 and P = 0.023, respectively).

According to the 2021 ESGO risk classification without molecular profiling, adjuvant radiation was associated with a significant improvement in PFS in the HIR group, but not in the IR group.