The advent of the neoadjuvant treatment, as well as the wide acceptance of surgical concepts such as, total mesorectal excision and resection of the circumferential margin, established the management of the rectal adenocarcinoma in a whole new level of excellence. It's main benefit lies in the control of the local recurrence. Therefore, to the adequate management of rectal tumors, it's essentially that the preoperative stage should be precisely determined. The aim of this study is to evaluate the effect of the neoadjuvant therapy, in patients with rectal adenocarcinoma, on the stage (TNM); as well as, authenticate the use of the magnetic resonance imaging in the loco-regional staging.