The impact of circulating tumor cells (CTCs) detection in metastatic breast cancer (MBC): Implications of “indolent” stage IV disease (Stage IVindolent).

Abstract

1019Background: CTCs count has been validated as a prognostic biomarker in MBC. In primary breast cancer, diagnostic tools exist to select less aggressive treatments in patients with indolent disease. In the largest CTC analysis to date, we define an indolent subset of patients in MBC, Stage IV indolent, identified using CTC counts. Methods: We performed a combined pooled analysis of individual patient data in two large cohorts: the European Pooled Analysis Investigators (EPAC) cohort (N = 1,944) and the MD Anderson Cancer Center (MDACC) cohort (N = 492). For all patients (N = 2,436), CTC enumeration was performed using the FDA-approved CellSearch™ (Menarini Silicon Biosystems, LLC) with baseline samples collected before starting a new treatment. Overall survival (OS) data were collected from both cohorts. Patients were stratified based on 5 CTCs/7.5 mL blood (N = 1,336 with < 5 CTC or Stage IV indolent; ≥5 CTC, Stage IV aggressive). Proportional hazards regression model and stratified log rank tests were...