Outcomes of medically inoperable endometrial cancer treated with Y-tandem brachytherapy

Summary: Purpose: Our goal was to evaluate the dosimetry, toxicity, and outcomes of medically inoperable endometrial cancer patients treated with EBRT and brachytherapy. Methods: 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). Results: A total of 19 patients were included in the study. Average body mass index (BMI), Charlson Comorbidity Index, and Karnofsky Performance Status (KPS) were 49.1, 6.0, and 76, respectively. Median total treatment time with EBRT and brachytherapy was 59 days. The mean EQD2 D2cc values to the surrounding organs at risk were 89.0 Gy to the bladder, 66.8 Gy to the small bowel, 71.2 Gy to the sigmoid colon, and 61.7 Gy to the rectum. Less than 20% of patients 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 recurrence-free survival (RFS) rate was 67%, and the two-year overall survival (OS) rate was 82%. Cox proportional hazards modeling indicates an association between longer total treatment duration and decreased overall survival (p=0.046). Conclusions: Brachytherapy with EBRT can be used to treat medically inoperable endometrial cancer patients with a minimal risk of severe toxicity. Overall survival may be decreased with extended total treatment time. Caitlin Reichard (she/her/hers), BA, MA (Presenting Author) - University of Louisville School of Medicine; Jeremy Gaskins, PhD (Co-Author) - University of Louisville Dept of Bioinformatics & Biostatistics; Maxwell Kassel, MS (Co-Author) - South Florida Proton Therapy Institute; Andres Portocarrero Bonifaz, MS (Co-Author) - Mayo Clinic Jacksonville; Scott Silva, MD, PhD (Co-Author) - University of Louisville Dept of Radiation Oncology