Inclusion Criteria:  Histological proven adenocarcinoma of the rectum cT2-3, N0-2 or cT4 for anal sphincter involvement N0-2a, M0 No prior radiotherapy in pelvic region; Tumour located between 0 and 15 cm above the anal verge; Not mesorectal fascia involvement for tumor No extramesorectal nodes involvement No extramural venous invasion (EMVI) No rectal mucinous adenocarcinoma histology No contra-indications for MRI Eastern Cooperative Oncology Group (ECOG) 0-1 Age over 18 years Adequate hematological function: granulocyte count > 1500/microl; Hemoglobin level > 10 g/dl; Platelet count > 100000/microl; Alanine Aminotransferase/ aspartate aminotransferase (ALT/AST): 7-45 UI/L; No other malignancies in the previous history (except skin and initial cervical cancer); Absence of important comorbidities: severe cardiac or coagulative disease, moderate or severe; restrictive/obstructive lung deficit, severe cognitive impairment, moderate and severe renal and hepatic impairment. Absence 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; Absence of pregnancy or lactating female patients; Written informed consent  Exclusion Criteria: not defined