Preoperative serum markers in carcinoma of the rectum and rectosigmoid. II. Prediction of prognosis.

The prognostic value of a single preoperative determination of the serum (S) concentration of carcinoembryonic antigen (CEA), tissue polypeptide antigen (TPA) and the carcinoma-associated carbohydrate antigen CA-50, either alone or in combination was evaluated in 327 consecutive patients with carcinoma of the rectum. A strong correlation was found between the serum level of each of these tumour markers separately, and prognosis, both in terms of crude survival in all patients and in disease-free survival in 'potentially cured' patients. The prognostic information provided by S-TPA and S-CA-50 was stronger, however, than that given by S-CEA. In a multivariate approach, S-TPA was found to be most informative. With use of the Cox regression model, the critical serum values that best separated patients in regard to mortality were CEA 18 micrograms/l, TPA 120 U/l and S-CA-50 40 U/ml. The critical values that best discriminated disease-free survival in 'potentially cured' patients were CEA 12 micrograms/l, TPA 110 U/l and S-CA-50 28 U/ml. The clinical usefulness of these and other cut-off levels is discussed.