Multicenter Phase 2 Trial: a Tailored Strategy for Locally Advanced Rectal Carcinoma

Inclusion Criteria: * Histologically confirmed rectal carcinoma * Primary tumor evaluated by pelvic MR Imaging: i) iT3 ≥c tumors, with MRI showing a predictive CRM ≤ 2 mm or a EMS (Extra Mural Spread) ≥ 5 mm ii) Resectable iT4 tumors (only randomized within the "poor responders" group) iii) Any T tumors with MRI showing a predictive CRM ≤ 1 mm * No detectable metastases: Thorax-abdomen-pelvic CT-scan * Patient ≥ 18 years * ECOG Performance Status 0-1-2 * Patient information and written informed consent form signed * Patient who can receive radiotherapy and chemotherapy * Negative pregnancy test in women of childbearing potential * Patient covered by a Social Security system * Hematology : Haemoglobin ≥ 9 g/dL, WBC ≥ 4000/mm3, neutrophils ≥ 1.5 x 109/L, platelets ≥ 100 x 109/L * Hepatic function : total bilirubin ≤ 1.5 x ULN, AST and ALT ≤ 3 x ULN, Alkaline phosphatases ≤ 3 x ULN * Renal function : creatinine ≤ 1.25 x ULN or creatinine clearance ≥ 60 ml/min Exclusion Criteria: * Indication for immediate surgery * Primary tumor not measured at the MRI before inclusion * Previous pelvic radiotherapy * Contraindication to radiotherapy and/or chemotherapy * Severe renal or liver impairment * Cardiac and/or coronary disease which could contraindicate 5-Fu administration * Active infectious disease * Peripheral sensitive neuropathy * History of prior cancer (except if it was cured more than 5 years ago, and if complete remission) * Patient (male or female) of reproductive potential not using an effective contraceptive method during the whole treatment and up to 6 months after the completion of treatment * Concurrent participation in any other clinical trial likely to interfere with the therapeutic schedule * Fertile female patient not using adequate contraception, or breast-feeding woman