Circulating tumour markers and time to progression in the chemotherapy treatment of metastatic breast cancer

Abstract

10674 Background: Monitoring the response to the chemotherapy treatment (CT) in metastatic breast cancer (MBC) by circulating tumour markers (CTM) remains under investigation. We have previosly shown that early lack of biological progression of 4 CTM (1 oncofetal: CEA, 2 mucin related: CA 15.3,CA 549 and cytokeratin 18–19: TPA), predicts anatomic disease control - concordance nearly 100% for every CTM- during CT of MBC (E.J.C. Suppl Oct 2005, Vol 3 Abst 415- ECCO 13). The aim is to evaluate whether the biological behaviour predicts time till progression (TTP), as reliable parameter of the quality of response (QR). Methods: In 106 consecutive courses of different schedules of CT given along 3 years in our Hospital to 55 patients with progressive MBC, we conducted a prospective trial analysing these 4 CTM every 3 weeks before CT infusions and performing CTM concentration / time curves. TTP was calculated by Kaplan Meier method -SPSS 11-. Bio kinetic change has been defined as a lineal slope that includes 2 early and consecutive changes of at least 25% of CTM start value. The analysis covered 604 cycles, 405 curves and 2417 marker determinations. Results: Ninety six per cent of the cases have progressed after their CT courses. In CTM expressing diseases, and sometimes after a no more than 3 weeks paradoxical period, three biological patterns could be detected according to directional possibilities: progressive elevation (Bio P), progressive download (Bio R) and stabilization -without bio kinetic change- (Bio S). Table shows the TTP median values in the different group of cases with the same CTM Bio response patterns; Biological Patterns and TTP Kaplan Meier curves will be shown as a Poster at the meeting. Conclusions: In CTM expressing tumours and taking into account simple kinetics criteria, the dynamic analysis of CTM before infusions can early estimates TTP, adding complemmentary information to the disease control prediction in the evaluation of the QR during the CT of MBC. [Table: see text] No significant financial relationships to disclose.