Standard care for locally advanced rectal cancer consists in a neoadjuvant therapy followed by surgery. Morbidity and mortality remain high after rectal surgery, and often linked with quality of life impairment. 10 to 30% present a pathological complete response after neoadjuvant therapy. Some surgical teams propose "watch and wait" approach for patients selected with clinical complete responses criterion. The problem is to be sur the response is complete. MRI seems to be accurate to select complete responders. We will try to find MRI criterion of complete responses.

Inclusion Criteria:

• Rectal adenocarcinoma
• Locally advanced
• Neoadjuvant therapy
• MRI restaging
• Rectal surgery
• Definitive anatomopathology study

Digestive surgery department