Prophylactic Extended-Field Irradiation Versus Pelvic Irradiation in Patients With Cervical Cancer With 2018 FIGO Stage IIIC1 Disease

Purpose: The aim of this study was to compare the survival rates and toxicities of prophylactic extended-field radiation therapy (EFRT) and pelvic radiation therapy (PRT) among patients with cervical cancer with 2018 International Federation of Gynecology and Obstet-rics (FIGO) stage IIIC1 disease. Methods and Materials: We retrospectively analyzed patients with 2018 FIGO stage IIIC1 disease who were treated with definitive concurrent chemoradiotherapy at our institute between 2011 and 2015. A dose of 50.4 Gy in 28 fractions was delivered to the pelvic region (by PRT) or the pelvic plus para-aortic lymph node region (by EFRT) with intensity modulated radiation therapy. The first-line regimen of concurrent chemotherapy was weekly cisplatin. Results: A total of 280 patients were included, with 161 patients treated with PRT and 119 patients treated with EFRT. After propensity score matching (1:1), 71 pairs of patients were selected. The respective 5-year rates of the patients treated with PRT and EFRT were 61.9% and 85.0% for overall survival (P = .025) and 53.0% and 77.9% for disease-free survival (DFS) (P = .004), respectively, after matching. In the subgroup analysis, patients were grouped into a high-risk group (122 patients) and a low-risk group (158 patients) based on 3 factors: positive common iliac lymph nodes, >= 3 pelvic lymph nodes, and 2014 FIGO stage IIIB disease. In both the high-risk and low-risk groups, EFRT significantly improved DFS compared with PRT. The rates of grade >= 3 chronic toxicities were 1.2% and 5.9% in the PRT and EFRT groups, respectively (P = .067). Conclusions: In comparison to PRT, prophylactic EFRT was associated with improved overall survival, DFS, and para-aortic lymph node control in patients with cervical cancer with FIGO stage IIIC1 disease. The incidence of grade >3 toxicities was higher in the EFRT group than in the PRT group, although the difference was not significant. (c) 2023 Published by Elsevier Inc. on behalf of American Society for Radiation Oncology.