title: Circulating tumor cells in breast cancer: a tool whose time has come of age.
abstract: Circulating tumor cells (CTCs) are isolated tumor cells disseminated from the site of disease in metastatic and/or primary cancers, including breast cancer, that can be identified and measured in the peripheral blood of patients. As recent technical advances have rendered it easier to reproducibly and repeatedly sample this population of cells with a high degree of accuracy, these cells represent an attractive surrogate marker of the site of disease. Currently, CTCs are being integrated into clinical trial design as a surrogate for phenotypic and genotypic markers in correlation with development of molecularly targeted therapies. As CTCs play a crucial role in tumor dissemination, translational research is implicating CTCs in several biological processes, including epithelial to mesenchymal transition. In this mini-review, we review CTCs in metastatic breast cancer, and discuss their clinical utility for assessing prognosis and monitoring response to therapy. We will also introduce their utility in pharmacodynamic monitoring for rational selection of molecularly targeted therapies and briefly address how they can help elucidate the biology of cancer metastasis.
authors.affiliation: Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111, USA. ramona.swaby@fccc.edu
authors.forename: Ramona F
authors.initials: RF
authors.lastname: Swaby
authors.forename: Massimo
authors.initials: M
authors.lastname: Cristofanilli
mesh_terms: D035843:Biomedical Research / Q000379:methods; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary; D002986:Clinical Trials as Topic; D003584:Cytological Techniques / Q000379:methods* / Q000592:standards; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006801:Humans; D009360:Neoplastic Cells, Circulating