Non Inferiority Study of Preoperative Chemotherapy Without Pelvic Irradiation for Rectal Cancer

Inclusion Criteria: * Histologically proven middle or low rectal carcinoma, ≤ 10 cm from the anal verge on MRI (sagittal slide) * cT3N0 and/or cT1-T3N+ on pretreatment imaging work up (pelvic contrast enhanced MRI and/or endorectal ultrasound), * Pretreatment predictive circumferential margin \> 2mm on pretreatment imaging work up (pelvic contrast enhanced MRI) * Patients must be 18 years old or older * A World Health Organization (WHO/ECOG) performance status of 0 or 1 * Informed consent signed * Patients of childbearing / reproductive potential should use adequate birth control measures during the study treatment period and for at least 6 months after the last study treatment. A highly effective method of birth control is defined as those which result in low failure rate (i.e. less than 1% per year) when used consistently and correctly. Exclusion Criteria: * Rectal tumor \> 10 cm from the anal verge on MRI (sagittal slide) * cT4 tumor on pretreatment imaging work up (pelvic contrast enhanced MRI and/or endorectal ultrasound) or involvement of external sphincter * Circumferential margin ≤ 2 mm on pretreatment imaging work up (pelvic contrast enhanced MRI) * Metastatic disease * Prior pelvic irradiation or any contraindication to pelvic irradiation * Contraindication to oxaliplatin or irinotecan or 5FU based chemotherapy * Concomitant treatment with warfarin is contraindicated and warafarin must be replaced whenever possible to allow for inclusion. * Recent or concomitant treatment with brivudine is contraindicated * contraindications to 5-FU: complete and permanent insufficiency in dihydropyrimidine dehydrogenase, bone marrow insufficiency, chronic and severe infection * contraindication to irinotecan : inflammatory bowel disease, bilirubin serum level \> 3 times the upper limit of the normal rate, severe bone marrow insufficiency, WHO/ECOG performence status \> 2, * Concomitant treatment with millepertuis. * contraindication to oxaliplatin : \*bone marrow insufficiency before treatment initiation (neutrophil count \<2x109/L and/or platelet count \<100x109/L), peripheral neuropathy with permanent invalidity before treatment initiation * severe renal insufficiency (Creatinin clearance \<30 ml/min) * contraindications to folinic acid : Biermer anemia and other anemia related to B12 vitamin insufficiency * contraindications to capecitabin : severe renal insufficiency (Creatinin clearance \<30 ml/min), complete and permanent insufficiency in dihydropyrimidine dehydrogenase * live attenuated vaccine should not be used during and 6 months after preoperative treatment. * Previous colorectal cancer * Other concomitant or previous malignancy, except: i/ adequately treated in-situ carcinoma of the uterine cervix, ii/ basal or squamous cell carcinoma of the skin, iii/ cancer in complete remission for \>5 years * Presence of any psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial * protected adults * Pregnancy or breastfeeding * Patient with no national health or universal plan affiliation coverage.