The role of circulating tumor cells in breast cancer diagnosis and prediction of therapy response

Background: Metastatic breast cancer (MBC) is incurable and any treatment is considered palliative. Occult dissemination of tumor cells is responsible for recurrent MBC in patients who have undergone resection of their primary tumor. The presence of circulating tumor cells (CTCs) in patients with MBC predicts progression-free and overall survival. Moreover, this prognostic value is independent of the line of therapy. Methods to detect and enumerate CTCs vary in sensitivity and specificity, and lack the standardization required for direct comparison between methods. Objective: To review the methods of detecting CTCs, the prognostic implications of CTCs, and opportunities to exploit the properties of CTCs to develop individualized therapy. Methods: The coupling of antibodies to immunomagnetic beads has facilitated the detection of low-frequency CTCs in peripheral blood of cancer patients. Results/conclusion: Standardization of methods will allow for the uniform detection of microscopic disease in the peripheral blood of patients with MBC and provide prognostic information that will allow appropriate risk stratification and modification of the current staging system for advanced disease.