Clinical significance of circulating tumor cells in breast cancer patients

Circulating tumor cells (CTCs) are defined as tumor cells circulating in the peripheral blood of patients, shed from either the primary tumors or its metastases. Many techniques have been developed in the recent years to identify CTCs in breast cancer patients, and trials have proved the prognostic significance of CTCs. In this study, we validated the CTC detection method of combining cell filtration and laser scanning cytometry (LSC), which was highly reproducible with increased sensitivity and accuracy. In 134 non-metastatic breast cancer patients analyzed, HER2 was found to be the only primary tumor characteristics that correlated with the presence of CTCs. 85 patients with definitive stage information were selected for association study between the disease stages and CTC numbers. The detection rate and the number of CTCs were correlated with the disease stages. Moreover, assessment of CTCs in 92 metastatic breast cancer patients was found to be able to predict the efficacy of chemotherapy. Increase in CTC numbers was an independent prognostic factor for treatment outcomes. Our results suggested that CTC assessment could be an indication of the disease progression and analysis of the properties of CTCs is likely to provide new insights into the biology of breast cancer and contribute to defining novel treatments and better prediction of clinical outcomes.