Presence of circulating tumor cells (CTC) in metastatic breast cancer (MBC) predicts rapid progression and poor prognosis

Abstract

524 Background: We have previously reported that the presence of 5 or more circulating tumor cells (CTCs) in 7.5 mL of blood from women with metastatic breast cancer (MBC) is associated with poor survival (NEJM, 351:8, 781–791, 2004). We have updated this multi-institutional prospective clinical trial and included data of CTCs at different time points after initiation of therapy. Methods: CTCs/7.5mL whole blood were enumerated at baseline and at 3 or 4 week follow-up intervals for a period of six months in 177 patients with MBC about to start a new systemic therapy. CTCs were immunomagnetically separated and fluorescently labeled using the CellSearch Kit. Only nucleated (DAPI+) cells with the phenotype EpCAM+, Cytokeratin 8, 18 and/or 19+, and CD45- were counted using the CellSpotter Analyzer. Results: Median Progression Free Survival (PFS) and Overall Survival (OS) were determined for patients with <5 or ≥5 CTC /7.5mL at baseline and specified intervals. Significance between the two groups of patients (logrank) and the percentage of patients that were alive at 12 months (AL12) after the blood draw is indicated in the table below. In multivariate analyses CTC remained the strongest and most significant independent predictor of poor outcome. Conclusions: Presence of CTCs before initiation of therapy in MBC patients with measurable disease is a strong predictor of survival and suggests that different therapeutic approaches should be used for these two subsets. Furthermore the persistence of CTCs after initiation of therapy suggests that the patients are on futile therapy and might, therefore, benefit from a change in regimen. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Immunicon Immunicon