Prophylactic Extended-Field Irradiation for Patients With Cervical Cancer Treated With Concurrent Chemoradiotherapy: A Propensity-Score Matching Analysis

OBJECTIVE: The aim of the study was to evaluate the efficacy and toxicity of prophylactic extended-field radiation therapy (RT) for cervical cancer patients treated with concurrent chemoradiotherapy (CCRT). METHODS: Records of patients with cervical cancer without para-aortic metastatic lymph nodes who were treated with definitive RT or CCRT between January 2011 and December 2014 were reviewed. Patients were classified into the pelvic RT and extended-field RT groups. An additional dose of 50.4 Gy in 28 fractions was delivered to para-aortic lymph node regions for patients in the extended-field RT group. Cox regression and propensity-score matching (1:1) were used to compare the overall survival (OS), disease-free survival (DFS), distant failure, and para-aortic lymph node failure (PALNF) between the pelvic RT and extended-field RT groups. RESULTS: A total of 778 patients were analyzed. Of them, 624 patients were treated with pelvic RT and 154 patients received extended-field RT. The median follow-up period was 37.5 months. In multivariate analysis, extended-field RT was an independent prognostic factor of distant failure (hazard ratio [HR] = 0.49, 95% confidence interval [CI] = 0.26–0.90, P = 0.023) and PALNF (HR = 0.012, 95% CI = 0.00–0.49, P = 0.019). However, it was not significant in predicting OS (P = 0.546) and DFS (P = 0.187). With propensity-score matching, 108 pairs of patients were selected. The 3-year OS, DFS, local control, distant failure, and PALNF rates in the pelvic RT and extended-field RT groups were 87.1% and 85.7% (P = 0.681), 71.0% and 80.6% (P = 0.199), 86.6% and 85.0% (P = 0.695), 21.7% and 7.0% (P = 0.016), and 6.6% and 0% (P = 0.014), respectively. The incidences of grade 3 or greater chronic toxicities were 3.5% and 6.5% in the pelvic RT and extended-field RT groups, respectively (P = 0.097). CONCLUSIONS: Prophylactic extended-field RT was associated with decreased distant failure and PALNF and showed a trend in improving DFS in patients with cervical cancer treated with CCRT.