The Potential of Circulating Tumor Cells in Personalized Management of Breast Cancer: A Systematic Review

Circulating tumor cells (CTCs) recognition and characterization in the peripheral blood of patients with breast cancer have proven practical and predictive value in different studies. However, the clinical significance of CTCs enumeration and molecular characterization in the personalization of breast cancer diagnosis and treatment remains under the debate. A literature search in PubMed, Web of Science and Scopus was performed from October 1990 to June 2016 for studies which evaluating CTCs and its association with clinical and pathological characteristics and medical outcome in the field of breast cancer personalization for both diagnosis and treatment categories. The treatment outcomes were progression-free survival (PFS) and overall survival (OS) or relapse in different patients. Sixty-nine studies met the inclusion criteria. The sample size varies from 1 to 2026. Median follow-up was 15 months (range 3-27). Different molecular techniques have been applied to research, but they mostly are based on CTCs enrichment and then detection by using FDA-approved Cell Search TM. By far the most studies define CTCs as cytokeratins (CK) positive and CD45 negative cells. Despite the differences in methodology, twenty-eight studies for breast cancer diagnosis and prognosis were mainly focused on CTCs isolation and enumeration. Forty-three researches were about CTCs count and exact molecular characterization. In the way of precision treatment, CTCs detection before starting the first-line of therapy or during therapy in breast cancer patients is extremely valuable, but in the way of precision medicine it should be supported with some molecular characteristics of CTCs like CTCs phenotypic changes, gene expression analysis of CTCs and molecular characteristics of CTCs