Preoperative serum markers in carcinoma of the rectum and rectosigmoid. I. Prediction of tumour stage.

Preoperative serum concentrations of carcinoembryonic antigen (CEA), tissue polypeptide antigen (TPA) and a monoclonal-antibody-defined carcinoma-associated carbohydrate antigen, CA-50, were measured in 272 consecutive patients with histopathologically proven rectal carcinoma. The levels of all three tumour markers correlated directly to the stage of the disease. The serum TPA reflected both the local tumour burden and any metastatic spread, as shown by analysing mean levels of S-TPA and by the use of a Walker and Duncan regression model. S-CA-50 separated patients with and without distant metastases, but not with regard to the local tumour burden. Although the level of S-CEA correlated to the tumour stage, it did not discriminate patients with respect to locally advanced growth or generalized disease. In a multivariate analysis, the serum level of TPA was found to be the most informative preoperatively. Both S-CA-50 and S-CEA gave information additional to that provided by S-TPA in the prediction of the tumour stage (Dukes' stage A-D), and S-CA-50 was also useful in the prediction of metastatic disease.