Modelling of serial carcinoembryonic antigen changes in colorectal cancer.

Carcinoembryonic antigen (CEA) is a tumour marker mainly used for detection of recurrent colorectal cancer. CEA series in 295 patients, who had a macroscopic radical resection of a primary colorectal cancer were studied. A kinetic model was fitted to CEA series of individual patients. Applying the kinetic model recurrences were identified with a sensitivity of 70-80% and specificity of 80-90%. Simulations were performed in order to find the optimal sampling strategy for CEA during follow-up. Simulations showed that CEA determinations at a few weeks interval between would be optimal for early detection of recurrences.