2830 - Preoperative Radiotherapy with or without Chemotherapy in the Management of Endometrial Cancer, Outcomes of Disease Control and Toxicity

Purpose/Objective(s): Current guidelines for the treatment of endometrial cancer generally involve therapeutic staging hysterectomy followed by adjuvant therapy or preoperative chemotherapy followed by hysterectomy for patients with extrauterine disease who are surgical candidates. However, there is minimal data currently available to guide treatment with preoperative radiotherapy. This retrospective study aims to highlight toxicity and disease control in a group of patients treated with preoperative radiotherapy +/- chemotherapy prior to hysterectomy.

Materials/Methods: After retrospective analysis of endometrial cancer patients treated at our institution, 16 patients treated with neoadjuvant therapy from 2019 to the present were identified. Patients were selected with the intention to treat with neoadjuvant radiotherapy +/- chemo followed by surgery. All patients received external beam radiotherapy 45-48.6Gy in 25-28fx +/- nodal boost, and 15/16 patients received HDR boost with a mean cumulative HRCTV D90% EQD2 of 77.05Gy (range 60.50-89.09). Of the 16 patients, 4 did not undergo surgery (2 with disease progression, 1 with metasynchronous cancer, and 1 death unrelated to cancer), and 12 underwent surgery at a median of 1 month after completion of radiotherapy (range 1-6). Of the 12 patients who received surgery, 11 received extrafascial hysterectomy, with 1 patient undergoing more extensive surgery due to concurrent rectal cancer.

Results: Final pathology of surgical specimens demonstrated a 100% margin negative rate. 50% of patients had a complete response. Of patients with residual tumor present, 33% had cervical stromal involvement. 25% of patients had nodes submitted to pathology, all negative for tumor. Median time of follow up after surgery was 16 months (range 1-54). Overall, 75% of patients remained in remission with no evidence of disease and a median DFS of 14.5 months (range 2-56). All disease recurrences occurred distantly, with locoregional control at 100%. Overall survival was 83%. Two (17%) patients were deceased at time of analysis with 1 death directly related to endometrial cancer. Of deceased patients, median time from diagnosis to death was 13 months. Grade 1-2 toxicity rate was 58% with 1 patient experiencing urinary incontinence, and 6 patients experiencing vaginal stenosis. No grade 3-5 toxicities were seen. 1 patient experienced a grade 3 rectovaginal fistula, however this patient was noted to have concurrent rectal cancer.

Conclusion: Neoadjuvant radiotherapy +/- chemotherapy followed by hysterectomy resulted in favorable outcomes in patients who had extrauterine disease at diagnosis. Locoregional control was 100% for patients who had completion surgery; all disease recurrences occurred distantly. Toxicity rates were low with majority of toxicity due to grade 1-2 vaginal stenosis.