Lumeneye Rectoscope for Assessment on Tumor Response After Total Neoadjuvant Treatment in Rectal Cancer

Inclusion Criteria: * Patient ≥ 18 years * Histologically confirmed diagnosis of adenocarcinoma of the rectum, * Patient who received radiotherapy and chemotherapy (TNT) or immunotherapy * Stage cT2T3 * cN0 or cN1 (≤ 3 positive LN or size ≤ 8 mm) * no metastases * Baseline Tumour size ≤ 5 cm (MRI) * Baseline Tumour ≤ 8 from anal verge * Ability to consent. * Oral agreement after reading information letter Exclusion Criteria: * Tumour cT1 or cT4 * Baseline Tumour size \> 5cm * Invaded external sphincter or levator muscle * Tumour cN2 (\> 3 positive LN or size \> 8 mm) * Metastasis * History of Inflammatory bowel disease * Patient with a history of pelvic radiotherapy or chemotherapy * Pregnant patients * Protected adults (individuals under guardianship by court order).