Locally advanced rectal carcinoma raise the issue of both the oncological control, local and general, and the therapeutic morbidity. Surgery alone can cure only one out of two patients, radiochemotherapy improves the local control but the metastatic risk remains about 30% with enhanced postoperative morbidity and poor functional results. The tumor response to preoperative treatment is the major prognostic factor which revealed the aggressiveness of the tumor. To this day, there are no biologic predictive markers for tumor response.