Plasma CEA in large bowel carcinoma: which patients should be followed by regular postoperative measurements? Preliminary follow-up results in 100 patients with different tumor DNA-ploidy patterns.

In 100 patients with large bowel carcinomas, the tumors were divided into a distinctly aneuploid (AN) group (63) and a near diploid (ND) group (37) by flow cytometric (FCM) DNA quantitation of cell suspensions. Preoperative plasma CEA levels were determined in all patients. Thirty-eight patients with AN and 28 patients with ND tumors were operated on for cure and had normal plasma CEA levels postoperatively. These two groups had regular CEA plasma measurements as part of the clinical follow-up. In the AN group, 12 of 15 patients have had recurrence preceded by CEA elevation. In the ND group, however, only one of eight recurrences was preceded by a rise in CEA level; the one with elevation also had increased plasma CEA prior to operation. It thus seems that a low CEA output of ND tumors explains many of the "false-negative" CEA measurements in disseminated cases. It is concluded that, in addition to patients with an elevated preoperative plasma CEA level, all patients with aneuploid tumors should be subjected to repeated plasma CEA measurements as part of the follow-up program.