Treatment Outcomes and Prognostic Factors of Metastasis-Directed Radiation Therapy for Oligometastatic Endometrial Cancer

Abstract

Purpose: To evaluate outcomes and prognostic factors associated with metastasis-directed radiation therapy (MDRT) for oligometastatic endometrial cancer. Methods and Materials: We retrospectively analyzed 101 patients (203 lesions) with <= 5 metastatic lesions treated with MDRT between 2015 and 2025. Oligometastatic states were classified according to the European Society for Radiotherapy and Oncology -European Organisation for Research and Treatment of Cancer framework. Endpoints were overall survival (OS), progression-free survival (PFS), and local failure-free survival. Prognostic factors were assessed using multivariable Cox regression, and toxicities were graded using the National Cancer Institute Common Terminology Criteria for Adverse Events v5.0. Results: At a median follow-up of 36.4 months, 3-year OS, PFS, and 2-year local failure-free survival rates were 76.3%, 24.5%, and 64.7%, respectively. Multivariable analyses revealed that favorable oligometastatic disease classification, endometrioid histology, favorable radiation therapy (RT) response, and maximum dose >= 40 Gy (equivalent dose in 2 Gy fractions, a/b = 10) were independently associated with improved OS. All factors, except for histology, were significant for PFS. In a propensity-matched analysis, repeated MDRT for recurrent oligometastases showed a trend toward improved OS compared with a single course. One grade 3 event occurred with no grade >= 4 toxicity. Conclusions: MDRT yielded favorable outcomes in oligometastatic endometrial cancer. Oligometastatic classification, histology, and RT response were major prognostic factors. MDRT may be a viable option within a multidisciplinary framework for de novo and recurrent oligometastases, but validation in prospective multicenter studies is warranted. (c) 2026 The Author(s). Published by Elsevier Inc. on behalf of American Society for Radiation Oncology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).