This phase III trial included patients with low rectal adenocarcinoma which initially required APR, with a mean clinical distance between the tumor inferior pole and the levator ani of 0.5 cm. Patients were randomly assigned to receive high-dose radiation (45 + 18 Gy) or radiochemotherapy (45 Gy + 5FU continuous infusion). The surgical decision was based on the tumor status at surgery. All surgeons used a homogenous SSR technique such as intersphincteric resection. The primary endpoint was the SSR rate.

Inclusion Criteria:

• Adenocarcinoma of ultra-low rectum at high risk of abdomino-périneal amputation
• Tumor classified as EER UT2-UT3, whatever the nodal status
• pathological confirmation of rectal adenocarcinoma without evidence of distant metastasis (M0), T2 or T3 resectable tumors without striated sphincter involvement and with the inferior margin of the tumor located less than 2 cm from the upper part of the levator ani.
• Age 18 years or older
• Informed and written consent

Exclusion Criteria:

• T1
• T4 (proven invasion of sphincter)
• Diffuse metastatic syndrome (no curative intent, short expected life span)
• preoperative incontinence (non due to the tumor)