A Prospective Study of 2-[18F] Fluoro-2-Deoxy-D-Glucose/Positron Emission Tomography Scan, 99mTc-Labeled Arcitumomab (CEA-Scan), and Blind Second-Look Laparotomy for Detecting Colon Cancer Recurrence in Patients With Increasing Carcinoembryonic Antigen Levels