This study aimed to evaluate the therapeutic efficacy of extended-field intensitymodulated radiotherapy (EF-IMRT) and dosage boost for positive lymph nodes, prognostic factors, treatment failure, and toxicity for Federation of Gynecology and Obstetrics (FIGO) stage IIICr and IVA cervical cancer patients with positive regional lymph nodes. Methods: We retrospectively evaluated 34 patients with stage IIICr and IVA who had received treatment in our institute between 2013 and 2016. Patients with

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... ge IVA cervical cancer who had been enrolled in the analysis all had positive regional lymph nodes (pelvic or/and para-aortic). All 34 patients were treated with EF-IMRT and simultaneously integrated boost-IMRT (SIB-IMRT) for lymph node metastasis with concurrent chemotherapy and brachytherapy. Positive regional lymph nodes (short-axis diameter ≥5 mm in computed tomography [CT] or magnetic resonance imaging [MRI]) remaining after SIB-IMRT were then treated with sequential boost-IMRT (SeB-IMRT). The prognostic factors for overall survival (OS); disease-free survival (DFS); local control rate (LCR); regional control rate (RCR); distant metastasis-free survival (DMFS), including age, FIGO stage, pretreatment hemoglobin (HB) level, tumor size, para-aortic lymph node (PALN) metastasis, point A equivalent dose in 2-Gy fractions (EQD2 dose), concurrent chemotherapy, and adjuvant chemotherapy cycles, were analyzed. Results: Complete response (CR) was achieved in 31 (91.2%) patients with acceptable adverse effects. Notably, the three-year OS, DFS, LCR, RCR, DMFS for these patients were 73.5%, 70.6%, 88.1%, 87.9%, and 81.6%, respectively. In particular, the three-year OS, DFS, LCR, RCR, and DMFS of patients with positive PALNs was 41.7%, 33.3%, 65.6%, 72.2%, and 60.2%, respectively. The corresponding values in patients without positive PALNs were 90.9%, 90.9%, 100%, 95.5%, and 90.9%, respectively. Conclusions: Our study suggested that the EF-IMRT and nodal dosage boost decreased regional node failure and that patients with stage IIIC1r and IVA cervical cancer without PALN metastasis who received EF-IMRT and SIB-IMRT with or without SeB-IMRT had a significant survival advantage in terms of the DFS and OS.