Treatment response in metastatic breast cancer. A multicentre study comparing UICC criteria and tumour marker changes

One hundred and twenty-nine patients with dissiminated breast cancer were selected to study the clinical applicability of changes in CA 15-3, tissue polypeptide specific antigen (TPS) and carcinoembryonic antigen (CEA) during therapy and how these compare with responses as assessed by UICC criteria in a multicentre study. The alterations in tumour marker levels followed the course of disease but indicated changes in the disease state earlier than clinical assessment (UICC criteria). Patients were grouped according to whether they had progressive disease (PD in groups III and IV), stable disease (SD in group II) or partial remission/complete remission (PR/CR in group I) during a treatment period of 6 months. The number of patients with a 50% decrease of the marker level, and the time at which this reduction was reached, was analysed in patient groups I–III. TPS showed this 50% decrease more frequently (69%) and also earlier (1.1 months) than either CA 15-3 (46% and 2.5 months) or CEA (47% and 1.7 months). The number of patients for whom marker levels increased by 25% or more was analysed in patient groups III and IV versus groups I and II. Such rises were seen more often in patients with progressive disease (TPS 82%, CA 15-3 62% and CEA 61%) than in patients with a more favourable prognosis (TPS 43%, CA 15-3 22% and CEA 24%). The dynamics of changes in tumour marker levels were different during treatment in patients with SD, PR or CR. However, the markers showed similar behaviour in patients developing PD during the study period. TPS appeared to indicate outcome somewhat better than did either CA 15-3 or CEA. Combined determination of CA 15-3 and TPS during therapy for metastatic breast cancer is recommended.