Post-chemoradiation intraoperative electron-beam radiation therapy boost in resected locally advanced rectal cancer: Long-term results focused on topographic pattern of locoregional relapse

Background Patients with locally advanced rectal cancer (LARC) have a dismal prognosis. We investigated outcomes and risk factors for locoregional recurrence (LRR) in patients treated with preoperative chemoradiotherapy (CRT), surgery and IOERT. Methods A total of 335 patients with LARC [⩾cT3 93% and/or cN+ 69%) were studied. In multivariate analyses, risk factors for LRR, IFLR and OFLR were assessed. Results Median follow-up was 72.6months (range, 4–205). In multivariate analysis distal margin distance ⩽10mm [HR 2.46, p=0.03], R1 resection [HR 5.06, p=0.02], tumor regression grade 1–2 [HR 2.63, p=0.05] and tumor grade 3 [HR 7.79, p<0.001] were associated with an increased risk of LRR. A risk model was generated to determine a prognostic index for individual patients with LARC. Conclusions Overall results after multimodality treatment of LARC are promising. Classification of risk factors for LRR has contributed to propose a prognostic index that could allow us to guide risk-adapted tailored treatment.