The Evolving Role of Circulating Tumor Cells in the Personalized Management of Breast Cancer: From Enumeration to Molecular Characterization

Abstract

Circulating Tumor cells (CTCs) represent tumor cells in the blood stream dislodged from the primary tumor. The presence of CTCs in the bloodstream provides a unique opportunity to sample cancer tissue by means of a relatively less-invasive “liquid biopsy.” Over the past decade, there has been a tremendous increase in the amount of research examining the potential clinical utility of CTCs in the management of cancer. A number of techniques to refine the sensitivity and range of CTC assays are also in development. In this article, we review the recent developments in the current and potential clinical applications of CTCs in breast cancer. CTC enumeration already has an established role as a prognostic biomarker in metastatic breast cancer, while molecular characterization of CTCs can serve as a potential predictive biomarker for therapy selection, pharmacodynamic evaluation, and identification of novel actionable targets for novel therapies. The role of CTCs in breast cancer screening and detection of recurrence is currently limited. Further development in techniques will be pivotal in enhancing the broad applicability of CTCs and advancing the field of personalized breast cancer therapy.

A Prospective Evaluation of Circulating Tumor Cells and Cell-Free DNA in EGFR-Mutant Non–Small Cell Lung Cancer Patients Treated with Erlotinib on a Phase II Trial

“…Finally, a robust literature continues to evaluate CTCs as a prognostic biomarker as well as a means of monitoring metastatic disease in breast cancer (39,40), but the data for prognostic use of CTCs in NSCLC have not been as clear thus far. In this study, we show that actionable genetic information can be obtained from both CTCs and cfDNA, consistent with a recent report demonstrating identification of the EGFR T790M mutation in evaluation of CTCs and cfDNA (19).…”

Liquid biopsy - emergence of a new era in personalized cancer care

“…Under physiological conditions, it increases the ability of the tumor cells to survive in blood circulation and establish micro-metastases in peripheral tissues. The process has been implicated in acquiring resistance to anti-cancer therapy and metastasis seen in resistant tumors [156].…”

The Clinical Relevance of Circulating Tumor Cells in Early Breast Cancer

“…However, the use of CTC presence as a screening tool to diagnose early breast cancer (EBC) is challenged by the low sensitivity of current CTC detection methods. Current CTC detection platforms such as the FDA-approved CellSearch™ system can only detect CTCs in about 70% of patients with metastatic breast cancer [5]. One of the solutions to improve sensitivity may be the previous performance of leukapheresis.…”