 - At the time of randomization, all patients must have had the following within the previous 42 days: history and physical examination; if technically feasible, a complete colonoscopic examination; if not feasible, a proctoscopic or sigmoidoscopic exam; clinical staging of the tumor; CT or MRI of the abdomen and pelvis combined PETCT may be substituted, and a chest x-ray PA and lateral or CT scan of the chest to exclude patients with metastatic disease. 