Usefulness of carcinoembryonic antigen monitoring despite normal preoperative values in node-positive colon cancer patients

PURPOSE: The aim of our study was to determine to what extent serial carcinoembryonic antigen (CEA) monitoring is helpful in detecting colorectal cancer recurrence in patients if their preoperative serum CEA is normal. Additional major objectives of this study were to correlate CEA immunohistochemical features of the primary tumor with serum CEA levels at the time of tumor recurrence in node-positive colorectal cancer patients with low preoperative CEA values. METHODS: One hundred fourteen node-positive colorectal cancer patients with preoperative serum CEA levels of <5.0 ng/ml undergoing clinically curative operations were studied. Primary tumors were evaluated for tissue CEA using the same monoclonal antibody as used for serum CEA determinations utilizing the avidin-biotin-peroxidase immunohistochemical technique. RESULTS: The exact preoperative serum CEA value did not correlate with tumor grade, immunohistochemical CEA intensity or pattern. In the 32 patients who developed recurrent cancer, the serum CEA at recurrence was greater than 5 ng/ml in 44 percent. All such patients had CEA present in their primary tumor. There was no correlation with the exact preoperative serum CEA, the intensity of the primary tissue CEA, or the localization of such CEA and subsequent serum elevation at recurrence. CONCLUSION: Serum CEA is a useful marker in the detection of recurrent colorectal cancer despite normal preoperative values.