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

feasibility of using a diffusion sequence of a MRgRT system as an early marker of treatment response during nRCT of rectal adenocarcinoma.

Inclusion criteria

• Patient over 18 years old.
• Diagnosis of histologically confirmed rectal adenocarcinoma for which nRCT has been indicated.
• Karnofsky Index (KPS) ≥ 70 or ECOG = 0 or 1
• Signed consent to participation.
• For women of childbearing age, effective contraception must also be agreed for the duration of treatment.
• Affiliation to a social security regimen, or beneficiary of such a regimen.

Exclusion criteria

• Predominant mucinous component on initial MRI, biopsy and / or definitive pathology. Mucin may lead to overestimation of ADC values on DWIs.
• Contraindications to the MRI procedure (non compatible pacemaker or other metallic foreign body, severe claustrophobia).
• Exclusive radiation therapy.
• Other associated neo-adjuvant treatment.
• Delayed completion of the surgery (more than approximately 10 weeks after the end of the nRCT) or cancellation of the surgical procedure.
• Contraindications to capecitabine: Severe hepatic impairment, severe renal impairment (creatinine clearance <30 ml / min),
• Known deficiency of Dihydropyrimidine dehydrogenase (DPD), known hypersensitivity to 5-FU / capecitabine and / or its excipients.
• Participation in a protocol with concurrent treatment.
• Pregnant or likely to be pregnant (without effective contraception) or breastfeeding
• Person in emergency situation, person of legal age subject to a legal protection measure, or unable to express his / her consent.
• Impossibility of attending the medical examination of the test for geographical, social or psychological reasons.