Kinetics of serum tumor marker concentrations and usefulness in clinical monitoring

Only a few markers have been instrumental in the diagnosis of cancer. In co ntrast, tumor markers play a critical role in the monitoring of patients. T he patient's clinical status and response to treatment can be evaluated rap idly using the tumor marker half-life (t(1/2)) and the tumor marker doublin g time (DT). This report reviews the interest of determining these kinetic parameters for prostate-specific antigen, human chorionic gonadotropin, alp ha-fetoprotein, carcinoembryonic antigen, cancer antigen (CA) 125, and CA 1 5-3. A rise in tumor markers (DT) is a yardstick with which benign diseases can be distinguished from metastatic disease, and the DT can be used to as sess the efficacy of treatments. A decline in the tumor marker concentratio n (t(1/2)) is a predictor of possible residual disease if the timing of blo od sampling is soon after therapy. The discrepancies in results obtained by different groups may be attributable to the multiplicity of immunoassays, the intrinsic characteristics of each marker (e.g., antigen specificity, mo lecular heterogeneity, and associated forms), individual factors (e.g., non specific increases and renal and hepatic diseases) and methods used to calc ulate kinetics (e.g., exponential models and timing of blood sampling). Thi s kinetic approach could be of interest to optimize patient management. (C) 1999 American Association for Clinical Chemistry.