5 x 5 Gy and consolidation chemotherapy vs long-course preoperative chemoradiation for locally advanced rectal cancer: An interim analysis of a randomized phase III study.

Abstract

e15006 Background: To present an interim analysis of a phase III trial comparing short-course radiotherapy followed by chemotherapy with long-course chemoradiotherapy in locally advanced rectal cancer. Methods: Patients with distal or middle third, MRI diagnosed cT3-T4 or N+ rectal adenocarcinomas were randomized to either 5 x 5 Gy and 4 courses of CAPOX (experimental group) or 50 Gy delivered in 25 fractions given concurrently with capecitabine (control group). Total mesorectal excision (TME) in both groups was performed 6-8 weeks after neoadjuvant treatment. This is an interim analysis of acute toxicities for the first 127 patients who finished neoadjuvant therapy, as well as the pCR and surgical complications for the first 100 patients who received surgery. Results: From 08/30/2015 to 12/11/2016, 63 patients in experimental group and 64 in control group from 10 Chinese hospitals were analyzed. During preoperative treatment, any acute toxicities were 100% in both groups and grade III-IV 19.0% vs. 6.3% ( p= 0.03) in experimental group and control group, respectively. Full-dose completion rates of planned neoadjuvant treatment were 88.9% and 93.7% in each group ( p= 0.33), respectively. After median duration of 7 weeks and 9 weeks in experimental group and control group, TME was performed. Among the 100 patients who have finished surgery, 94.1% and 89.8% in experimental and control group had R0 resection ( p= 0.426), while 21.6% and 6.1% of them achieved pCR ( p= 0.026), respectively. There were 8 patients in experimental group diagnosed as clinical CR and refused to further radical surgery, while, none in control group ( p= 0.003). The incidences of surgical complications were similar between two groups (experimental 29.1% vs. control 26.5%; p= 0.748), with perineal healing delay as the main reason. Conclusions: The acute toxicity and surgical complication were acceptable and comparable in both groups, however, the people in experimental group showed a significantly clinical and pathological response. The short-course irradiation and consolidation chemotherapy maybe an alternative standard of care, though the final result is in prospect. Clinical trial information: NCT02533271.