Table 5.

Potential future applications of CTC detection and characterization.

Early BC

Metastatic BC

CTC detection might improve prognostication and help to identify patients in need of aggressive therapy and/or bisphosphonates CTC persistence might serve as stratifying parameter to select patients who benefit most from extended endocrine treatment Patients with CTC persistence beyond adjuvant chemotherapy might potentially benefit from secondary adjuvant treatment Evaluation of predictive markers on CTCs might serve as basis for treatment decisions: e.g., patients with HER2-negative primary tumor but HER2-positive CTCs might benefit from HER2-targeted therapy

Detection of high CTC levels and thus worse prognosis might become a valuable information for improved care planning in palliative setting CTC detection after start of a new line of chemotherapy helps to predict response to treatment early; patients with high CTC levels might either be switched to another therapy approach (benefit so far not confirmed in trials) or to best supportive care to avoid unnecessary toxicity Evaluation of CTCs may serve as a liquid biopsy and thus render invasive biopsy of metastasis unnecessary; serial CTC measurements might provide continuous insight into current status of the disease