Monitoring Treatment Response With On-board DWI During Neo-adjuvant Chemo-radiation for Rectal Cancer Using Magnetic Resonance-guided-radiotherapy Systems

Eligibility Criteria

• 1. Patient over 18 years old.
• 2. Diagnosis of histologically confirmed rectal adenocarcinoma for which nRCT has been indicated.
• 3. Karnofsky Index (KPS) ≥ 70 or ECOG = 0 or 1
• 4. Signed consent to participation.
• 5. For women of childbearing age, effective contraception must also be agreed for the duration of treatment.
• 6. Affiliation to a social security regimen, or beneficiary of such a regimen.
• 1. Predominant mucinous component on initial MRI, biopsy and / or definitive pathology. Mucin may lead to overestimation of ADC values on DWIs.
• 2. Contraindications to the MRI procedure (non compatible pacemaker or other metallic foreign body, severe claustrophobia).
• 3. Exclusive radiation therapy.
• 4. Other associated neo-adjuvant treatment.
• 5. Delayed completion of the surgery (more than approximately 10 weeks after the end of the nRCT) or cancellation of the surgical procedure.
• 6. Contraindications to capecitabine: Severe hepatic impairment, severe renal impairment (creatinine clearance \<30 ml / min),
• 7. Known deficiency of Dihydropyrimidine dehydrogenase (DPD), known hypersensitivity to 5-FU / capecitabine and / or its excipients.
• 8. Participation in a protocol with concurrent treatment.
• 9. Pregnant or likely to be pregnant (without effective contraception) or breastfeeding
• 10. Person in emergency situation, person of legal age subject to a legal protection measure, or unable to express his / her consent.
• 11. Impossibility of attending the medical examination of the test for geographical, social or psychological reasons.