Definitive Radiation Therapy for Medically Inoperable Endometrial Cancer

Abstract

The standard of care for patients with endometrial cancer typically involves upfront surgery. External beam radiotherapy, brachytherapy, and/or chemotherapy are implemented in the adjuvant setting based on individual risk factors. In the subset of women who are unable to receive surgery due to medical comorbidities or tumor-related factors, external beam radiation and/or uterine brachytherapy can be employed in the definitive setting. To evaluate the clinical outcomes from definitive radiation therapy in women with newly diagnosed, medically inoperable, endometrial cancer. We used an institutional endometrial cancer database to identify medically inoperable patients who received definitive radiation therapy from 1999-2018. Kaplan-Meier method was used to calculate overall survival, cause-specific survival, and locoregional recurrence free survival. Cox regression analysis was used to assess variables associated with these outcomes. Forty-four patients were identified, with a median follow up of 29.1 months. Median age was 68 years (R: 40-90) and the median body mass index (BMI) was 43 (R:23-88). Ten patients (22.7%) had FIGO grade 3 disease. One patient received external beam radiation to the pelvis alone, twenty-seven patients underwent brachytherapy alone, and sixteen patients received combined external beam radiation to the pelvis followed by consolidative uterine brachytherapy. Chemotherapy was delivered in the neoadjuvant setting in two patients, adjuvant in one patient, and concurrently in two patients. 55% of patients had PET/CT and/or MRI based treatment planning. Four patients were unable to complete their intended treatment course due to exacerbation of medical comorbidities (2), progression of disease during treatment (1), or uterine perforation (1). Locoregional recurrence free survival was 92% (95% C.I. 83.7-100%) at 2 years. Cause-specific survival and overall survival were 79.3% (95% C.I. 65.8-95.7%) and 62% (95% C.I. 48.8-78.7%) respectively at 2 years. On univariate analysis, Grade 3 disease, age, and the presence of lymphadenopathy were associated with decreased overall survival, while surprisingly, BMI was associated with improved OS. KPS less than 80, radiotherapy technique, and smoking status were not associated with OS. On multivariate analysis, only the presence of lymphadenopathy remained significant. No variables were significantly associated with locoregional recurrence. There were no acute grade 3 toxicities observed in this cohort. Grade 3 toxicity was seen in 7.8% of patients with sufficient long term follow up. Definitive radiation therapy for endometrial cancer in medically inoperable patients is associated with excellent locoregional control and cause-specific survival. Cause-specific survival was considerably longer than overall survival in this cohort, suggesting that these patients frequently succumb to other medical conditions.