Locoregional Control Following Adjuvant Chemotherapy and Radiotherapy for Treatment of High-Risk Endometrial Cancer

Abstract

<h3>Purpose/Objective(s)</h3> Patients with locally advanced stage and aggressive histology endometrial cancer are at high risk of relapse, and usually treatment includes surgery, chemotherapy and radiotherapy. The timing and coordination of chemotherapy and radiotherapy remain controversial, though historically we have delivered adjuvant radiotherapy after completion of chemotherapy. The premise being to avoid delaying chemotherapy, which confers an overall survival benefit. We decided to review oncologic outcomes and patterns of recurrence among our patients and compare them with the published literature. <h3>Materials/Methods</h3> A retrospective review was conducted to evaluate patients who underwent primary surgery for endometrial cancer between 2005 and 2017, had a final pathology demonstrating Stage I-II endometrial cancer of serous or clear cell histology, Stage III endometrial cancer of any histology or Stage IV endometrial cancer of endometrioid adenocarcinoma histology, and were considered appropriate for adjuvant chemotherapy and radiotherapy. Kaplan-Meier analysis was used to calculate progression-free survival (PFS) and overall survival (OS). <h3>Results</h3> A total of 140 patients met the eligibility criteria and were included, with a median age of 65. The distribution according to stage was as follows: 41 (29.3%) Stage I, 24 (17.1%) Stage II, 68 (48.6%) Stage III, and 7 (5.0%) Stage IV. Of these patients, 52 (37.1%) had endometrioid, 75 (53.6%) had serous, and 11 (7.9%) had clear cell histology. All patients received chemotherapy with the median start time being 49 days after initial surgery. In total, 120 (92%) completed 6 cycles of chemotherapy. The median start time for radiotherapy was 35 days after chemotherapy and 192 days after surgery, with 129 (92.1%) completing adjuvant radiotherapy. The median dose of external beam radiotherapy (EBRT) was 4500 cGy in 25 fractions and the median dose of vaginal brachytherapy, when used, was 1800 cGy in 3 fractions. In terms of EBRT technique, 54 were treated with traditional conformal fields and 74 with IMRT techniques. The median follow-up was 63.9 months and the 5-year PFS and OS rates were 69% and 66% respectively. A total of 42 patients (30.0%) developed a recurrence; of which 2 (1.4%) were local, 10 (7.1%) were locoregional (any with component of locoregional failure), 8 (5.7%) were isolated para-aortic and 27 (19.3%) were distant. Among the 129 patients receiving radiotherapy, 6 (4.6%) patients had locoregional failure. Only 7 (5.4%) of patients had an "in-field" recurrence after EBRT, with 4 (3.1%) among patients treated with conformal fields and 3 (2.3%) among those treated with IMRT. <h3>Conclusion</h3> Adjuvant radiotherapy given after completion of surgery and adjuvant chemotherapy leads to favorable outcomes with regards to PFS and OS (compared to published randomized studies), and still results in excellent locoregional control.