Inclusion Criteria:  Histologically confirmed diagnosis of adenocarcinoma of the rectum Clinical Stage II (T3-4, N-) or Stage III (any T, N+) based on Magnetic Resonance Imaging (MRI) Tumors < 7cm from anal verge (palpable) No prior history of rectal cancer  Exclusion Criteria  Patients with tumors >7cm from anal verge ECOG >1, Contraindication for chemotherapy: Hemoglobin <8, White Blood Count <4000, Platelets <100,000, Creatinine Clearance <50ml/min, Total Bilirubin <5mg/dl, Stage IV at diagnosis Coronary artery disease, either no treated or recent acute coronary syndrome in the last 12 months. Congestive heart failure Peripheral neuropathy Previous pelvic radiotherapy Prior rectal cancer treatment Pregnancy or nursery Any contraindications to MRI (e.g. patients with pacemakers) Indication of pelvic exenteration Impossibility to consent.