Serum tumor marker kinetics and the clinical course of patients with advanced breast cancer.

Serum carcinoembryonic antigens (CEA), CA 15-3, and tissue polypeptide antigens (TPA) have been used in monitoring the clinical course of patients with breast cancer. However, recent reports have suggested that the serial levels of these markers during therapy do not always correlate with the response to therapy. To clarify the usefulness of the serial combination assay of these markers in monitoring the clinical course of patients during therapy, we investigated the relationship between the initial changes and the kinetic patterns of the markers after therapy and the objective responses. When an increase or decrease of over 20% in these markers is taken to be significant, then the initial changes in all three markers significantly correlated with the therapeutic responses (P < 0.01). Five distinct kinetic patterns in the marker levels were observed. A paradoxical kinetic pattern of CEA and CA 15-3 levels--that is, an "initial surge and subsequent drop"--was seen in one-third of the responders. The TPA levels tended to exhibit a "steady decline" pattern in those responders. The sensitivity and specificity of the kinetic patterns to predict the clinical courses were significantly higher than those obtained from the analysis of initial changes. These findings thus suggest that adequate knowledge of the unique kinetics of each marker may help to make a more accurate prediction of the therapeutic responses.