THeragnostic Utilities for Neoplastic DisEases of the Rectum by MRI Guided Radiotherapy

Inclusion Criteria: * Histological proven adenocarcinoma of the rectum; * cT2-4, or cN0-2 (also extramesorectal nodes), or mesorectal fascia involvement for tumor (MRF+) or extramural venous invasion (EMVI+); * cM0; * 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; * ECOG 0-1; * Age over 18 years; * Adequate hematological function: granulocyte count \> 1500/microl, Hemoglobin level \> 10 g/dl, Platelet count \> 100000/microl, 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: * Distant metastases (cM1); * Prior radiotherapy in the pelvic region; * Tumour located lower than 0 cm or higher than 15 cm above the anal verge; * Rectal mucinous adenocarcinoma histology; * Contra-indications for Magnetic Resonance Imaging (MRI); * Eastern Cooperative Oncology Group (ECOG) performance status score \>= 2; * Age under 18 years; * Inadequate hematological function (Granulocyte count \<= 1500/microl, Hemoglobin level \<= 10 g/dl, Platelet count \<= 100000/microl, ALT/AST outside 7-45 UI/L); * History of other malignancies (except skin cancer and initial cervical cancer); * Presence of severe comorbidities (severe cardiac or coagulative disease, moderate or severe restrictive/obstructive lung deficit, severe cognitive impairment, moderate/severe renal or hepatic impairment); * Any psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; * Pregnant or lactating female patients.