Résumé
Abstract only 483 Background: There are controversial data on the impact of a long waiting period between radiochemotherapy (RCT) and resection for rectal cancer on the rate of complete pathological response (pCR = ypT0N0). The impact on the oncological prognosis is also unknown. We present the 3 years survival results of the GRECCAR6 trial. Methods: The GRECCAR6 trial was a phase III, multicentre, randomized, open-label, parallel-group, controlled trial. Patients with cT3/T4 or TxN+ tumours assessed by radiological examination (MRI and/or endo-ultrasound) of the mid or lower rectum who had received RCT (45-50 Gy with intravenous 5-FU or capecitabine) were included and randomized between 7 weeks or 11 weeks of waiting period. Primary endpoint was the pCR rate. Secondary endpoints were overall, disease-free survival and rate of recurrences. Results: A total of 265 patients from 24 participating centres were enrolled between October 2012 and February 2015. Among them, 253 patients underwent surgery with mesorectal excision. The rate of pCR was 17% (43/253). Mean follow-up from surgical resection was 32±8 months. 25 deaths occurred with a 89% OS at 3 years. DFS was 67.7% at 3 years due to 77 deaths or recurrences. 3-years local and distant recurrences rates were 9.2% and 24.9%, respectively. The group of randomization had no impact on the OS (p = 0.9486) and the DFS (p = 0.8672). Distant (p = 0.8589) and local (p = 0.5780) recurrences were also not influenced by the waiting period. Patients with a pCR had an excellent prognosis with an overall survival of 94.5% versus 87.9% for the remaining patients at 3 years (p = 0.232) and a DFS of 89.6% versus 63.4% (p = 0.0025). On multivariate analysis, DFS was influenced by low rectal tumors (OR=1.74; [1.03; 2.94], p = 0.037), R1 resection (OR = 2.03; [1.18; 3.50], p = 0.011), ypT3-T4 (OR = 2.4; [1.12; 5.19], p = 0.0245) and N+ (OR = 2.85; [1.76; 4.61], p < 0.001). Conclusions: Waiting 4 weeks longer after radiochemotherapy has no influence on the oncological outcomes of T3/T4 rectal cancers. Clinical trial information: NCT01648894.