CEA tissue staining in colorectal cancer patients. A way to improve the usefulness of serial serum CEA evaluation.

The evaluation of serial plasma carcinoembryonic antigen (CEA) levels is one of the most important parameter used to establish the prognosis of surgically cured colorectal cancer patients. Carcinoembryonic antigen is particularly useful in the identification of recurrences and metastasis. However, to improve the usefulness of this assay, it would be helpful to accurately determine, if possible, those patients whose cancers produce CEA. The evaluation of the presence of CEA in these cancer specimens by means of immunoperoxidase staining technique does seem to improve the sensitivity of the CEA test. Fifty-seven patients with colorectal cancer who underwent surgical treatment were studied. Tissue CEA evaluation was correlated with the plasma CEA levels, the pathologic stage and grade, and histologic type of the cancers. Results demonstrate that 66.6% of Dukes' B cancers, 78.9% of Dukes' C, and 77.7% of Dukes' D cancers stained positively for CEA by immunoperoxidase. Thirty of 57 patients with preoperative pathologic plasma CEA levels had positive tissue CEA, whereas 8/57 patients did not. Of patients with a well-differentiated cancer (G1), 81.4% had positive tissue CEA versus the 64% of G2 and 60% of G3 cancers. The authors conclude that the use of the immunoperoxidase stain to measure CEA in tissue, so that the CEA serum assay may be used in those patients known to produce CEA, results in a major increase in the sensitivity of the test.