Dosimetry, Toxicity, and Outcomes of Medically Inoperable Endometrial Cancer Treated With Definitive External Beam...

Our goal was to evaluate the dosimetry, toxicity, and outcomes of medically inoperable endometrial cancer patients treated with external beam radiation therapy (EBRT) and brachytherapy.

A single-institution retrospective chart review was performed to identify patients with medically inoperable endometrial cancer who underwent EBRT and brachytherapy from 2009 to 2024. Patient demographics, tumor characteristics, and radiation dosimetry data were collected. Toxicities were defined using the Common Terminology Criteria for Adverse Events (CTCAE version 5.0). Outcomes evaluated included overall survival (OS) and recurrence-free survival (RFS).

A total of 19 patients were included in the study. Median body mass index (BMI), Charlson comorbidity index, and Karnofsky performance status (KPS) were 50 kg/m², 6.0, and 80, respectively. Median total treatment time with EBRT and brachytherapy was 59 days. Assuming an α/β ratio of 3, the median EQD2 (equivalent dose in 2 Gy fractions) D2cc (minimum dose received by the maximally irradiated 2 cc volume) values to the surrounding organs at risk were 85.9 Gy to the bladder, 64.4 Gy to the small bowel, 69.7 Gy to the sigmoid colon, and 60.1 Gy to the rectum. Less than 20% of patients (n=3) experienced acute or late grade 3 toxicities; 71%, 57%, and 79% of patients experienced no late gastrointestinal, genitourinary, or vaginal toxicities, respectively. In the overall patient cohort, the two-year RFS rate was 67%, and the two-year OS rate was 82%. Cox proportional hazards modeling indicates an association between longer total treatment duration and decreased OS (p=0.046).

Brachytherapy with EBRT can be used to treat medically inoperable endometrial cancer patients with a minimal risk of severe toxicity. OS may be decreased with extended total treatment time.