CEA--a concept worth exploring

We believe patients who have elevated CEA levels before resectioning procedures and who also have documented cancer of the gastrointestinal tract, with a subsequent drop in normal CEA levels postoperatively, should have sequential monthly determinations of colonic embryonal antigens. If there is an increase in levels of concentration, there is at that time justification for surgical intervention. The earlier the detection of elevated colonic embryonic antigen is accomplished, the better are the odds for a successful surgical resection of recurrent disease. The values of the CEA studies define slopes which can identify local recurrence and liver metastasis. For these slope values, it is necessary that the CEA level be drawn regularly. We consider this a promising real clinical advance in that it permits for better utilization of the two significant therapeutic modalities we have for the treatment of cancer of the gastrointestinal tract, namely resectional surgery and radiation therapy. CEA determinations have false positives and limited specificity. It is unfortunate that adult tissues express fetal antigens under conditions wherein there are bursts of cellular activity. This should not diminish the significance of tumor-embryo cross reactivity. This reactivity phenomenon is, in the words of Sir Peter Medawar, "a now well attested empirical fact," and this observation is "profoundly interesting and potentially important." The eventual significance of this fact may well transcend current use of the CEA in the diagnosis of recurrent cancer of the gastrointestinal tract.