Circulating tumor cells in breast cancer: Advanced tools for “tailored” therapy?

Alterations in oncogenes and suppressor genes are critical steps in carcinogenesis and tumor progression in solid and hematological malignancies. The development of therapeutic strategies that interfere with the functional pathways regulated by these genes represents the most successful example of targeted therapy (e.g., imatinib in chronic myelogenous leukemia and trastuzumab in breast cancer) (1, 2). In this issue of PNAS, Meng et al. (3) raise interesting possibilities for exploring circulating tumor cells (CTCs) for personalizing targeted therapy of cancer in the future.