(ChemotherapyAdvisor) – Blood tests might fail to detect rare circulating tumor cells, according to a group of researchers from The Ohio State University who presented their finding at the Annual Meeting of the American Association for Cancer Research (AACR) on April 2. The study, entitled “Circulating cancer associated cells co-express epithelial and hematopoietic markers in metastatic breast cancer (MBC) patients”, is listed as abstract No. 2371, and was presented by Maryam B. Lustberg, MD, MPH, study investigator and assistant professor of internal medicine at The Ohio State University College of Medicine.
Prior to this study being published, circulating tumor cells (CTCs) had been most commonly isolated by employing positive selection enrichment techniques that target the epithelial cell adhesion activating molecule (EpCAM). This technique defines a CTC as EpCAM and cytokeratins (CK) positive (+) and CD45 negative (-). However, according to the study authors, other rare cancer associated cells (RCACs) including EpCAM-negative and/or CD45+ cells have been reported. In this presentation, the authors reported on a prospective study evaluating RCACs in MBC.
Blood samples were collected from 40 MBC patients; 21 samples were from patients with estrogen receptor (ER) -, progesterone receptor (PR) -, and HER2neu non-overexpressing, or triple negative breast cancer (TNBC); 19 were from patients with ER/PR+, HER2neu non-overexpressing disease.
“In addition to CTCs, RCACs that are CD45+ and/or EpCAM- are detectable in MBC patients and more frequently present in TNBC patients. These populations, only detectable by negative depletion, may be clinically significant as ongoing studies evaluate the predictive capabilities of blood-based biomarkers,” the authors wrote.