Serum tumour markers CA 15-3, TPA, TPS, hCG beta and TATI in the monitoring of chemotherapy response in metastatic breast cancer

The clinical utility of CA 15-3, polypeptide specific antigen (TPS). tissue polypeptide antigen (TPA), human chorionic gonadotropin (hCG beta) and tum our-associated trypsin inhibitor (TATI) as indicators of chemotherapy respo nse was assessed in advanced breast cancer. Serum was prospectively collect ed in one center before treatment (after the first course of chemotherapy) and at response evaluation from 57 patients taking part in a multicentre ra ndomized trial comparing docetaxel with sequential methotrexate and 5-fluor ouracil in the treatment of advanced breast cancer. The pretreatment levels of the serum markers were not predictors of the later response to treatmen t. Changes in the TPS level showed the strongest association with clinical response after the first course of chemotherapy and CA 15-3 at the best res ponse evaluation. However. distinct mismatches occurred with every marker. The most problematic error was an increase in marker levels in patients wit h clinical responses, which might have caused interruption of therapy. This occurred in 8% and 17% of patients after the first course of chemotherapy and in 4% and 17% of patients at the best response evaluation with CA 15-3 and TPS, respectively. Moreover, after the first course of chemotherapy onl y 39% and 33% of the patients with progressive disease could be identified on the basis of increasing levels of CA 15-3 and TPS, respectively. Later, at clinical disease progression, TPA and TPS were found to be better indica tors of disease progression than CA 15-3. In conclusion, changes in CA 15-3 or TPS levels usually correlate with clinical response, but owing to disti nct discordances, they should not be used as sole indicators of response to chemotherapy in advanced breast cancer.