Addition of Postoperative Radiation Therapy After Preoperative Chemotherapy and Surgery in Patients With Locally Advanced Endometrial Cancer Is Associated With Improved Outcomes

Purpose: Our purpose was to examine outcomes of patients with locally advanced endometrial cancer who undergo neoadjuvant chemotherapy followed by surgery (PreCT) with/without postoperative adjuvant radiation therapy. A secondary analysis of down staging and margin clearance was made with reference to those receiving upfront surgery and then adjuvant chemotherapy (PostCT). Methods and Materials: The National Cancer Database was queried for FIGO (The International Federation of Gynecology and Obstetrics) stage III/IV locally advanced endometrial cancer cases who underwent definitive surgery from 2010 to 2016 and received chemotherapy as part of their treatment. Cases were classified into 2 cohorts: preoperative chemotherapy +/- postoperative chemotherapy cohort (PreCT) and postoperative chemotherapy cohort (PostCT) for reference for margin assessment. Cases who received preoperative radiation therapy were excluded while those who received postoperative radiation were included in the analysis. Primary endpoints were overall survival (OS), surgical margin status, rate of downstaging, and effect of adjuvant radiation therapy on OS among the PreCT cohort. Univariable (UVA) and multivariable (MVA) Cox regression analyses were performed. Results: A total of 13,369 cases were identified with 1059 in PreCT and 12,310 in PostCT cohorts. PreCT had lower OS than PostCT (UVA: hazard ratio [HR], 2.18; P < .001; MVA: HR, 1.873; P < .001). PreCT cases with negative margins, who presumably had unresectable tumors initially, also had worse OS compared with PostCT with negative margins (UVA: HR, 2.20; P < .001; MVA: HR, 1.84; P < .001); however, PreCT with negative margins had similar survival to PostCT with positive margins (UVA: HR, 0.825; P < .001; MVA: P = .885). The addition of radiation after surgery in the PreCT cohort was associated with improved survival (5-year OS 20.5% compared with 50%, respectively; UVA: HR, 0.450; P < .001; MVA: HR, 0.337; P < .001). Although fewer cases in PreCT had negative margins compared with PostCT (72% compared with 84%, P < .001), approximately 19% of cases in PreCT had lower pathologic T-stage compared with clinical T-stage and 11% had lower N-stage. Conclusions: Neoadjuvant chemotherapy was given in cases with worse oncologic prognostic factors, many of whom were likely unresectable at outset, compared with those who received postoperative chemotherapy. Although neoadjuvant chemotherapy is associated with tumor downstaging, survival is lower than with primary surgery probably because of these baseline differences. The addition of adjuvant radiation after surgery in cases who received preoperative chemotherapy is associated with improved survival.