Evaluation of the efficacy of prophylactic extended field irradiation in the concomitant chemoradiotherapy treatment of locally advanced cervical cancer, stage IIIB in the 2018 FIGO classification

BACKGROUND: The new staging system of cervical cancer issued in 2018 by the International Federation of Gynecology and Obstetrics (FIGO), calls for a new evaluation of the efficacy of prophylactic extended field irradiation (EFI) in the concomitant chemoradiotherapy/brachytherapy treatment of locally advanced cervical cancer patients (stage IIIB). METHODS: We performed a retrospective study consisting of 133 FIGO IIIB cervical cancer patients treated in the Peking Union Medical College Hospital from 2002 to 2010. The patients were distributed in two groups depending whether they were treated with EFI or pelvic only irradiation. The therapeutic efficacy, toxicity and prognostic factors of EFI were evaluated in the frame of the new FIGO staging system. RESULTS: When compared to patients who received pelvic only irradiation, patients who received prophylactic EFI showed significantly less distant metastasis and a significant improvement in their 5 years overall survival (OS), disease free survival (DFS), out of field recurrence free survival (OFRFS) and para-aortic lymph node metastasis free survival (PALNMFS). Multivariate analysis revealed that EFI is an independent prognosis factor for DFS, OFRFS and PALNMFS. Finally, although more acute complications were observed in the EFI group, there is no significantly worst acute toxicity in the EFI group. CONCLUSION: Our retrospective analysis supports the prophylactic effect of EFI in the concomitant chemoradiotherapy treatment of IIIB patients and suggests that this prophylactic effect is associated with a clear improvement in 5-years OS, DFS, OFRFS and PALNMFS. Consequently, EFI appears to be a very valid treatment option for FIGO IIIB cervical cancer patients.