Prognostic significance of CEA in colorectal cancer: a statistical study.

Pretreatment and serial posttreatment carcinoembryonic antigen (CEA) serum levels were studied with respect to the course of disease in 222 patients with colorectal cancer. The CEA values during the subsequent six years were expressed in actuarial or cumulative plots in relation to tumour-free period, time of diagnosis of recurrence and other parameters. The pretreatment CEA value was highly significant but gave no more prognostic information than the Dukes classification. The pretreatment CEA had prognostic significance only in inoperable patients. Elevated pretreatment CEA did not exclude the possibility of curative treatment. Normalization of CEA after resection did not indicate completeness of cure. In patients with local or distant recurrences CEA occasionally rose before recurrences became clinically apparent. Positive lead time was 0-625 days. However, in about 40% of the patients clinical diagnosis of recurrence preceded a rise of CEA. Maximal negative lead time was 585 days. Statistically, recurrence without a rise of CEA was exceptional. The results strongly suggest that serial CEA determinations cannot replace physical examination and follow-up.