The Clinical Significance of Circulating Tumour Cells in Breast Cancer and Colorectal Cancer Patients

Background: Circulating tumour cells (CTC) in the blood of cancer patients indicate disease progression. Their presence reflects a relapse or metastasising process since CTC survive only a short time in the circulation. Materials and Methods: Test systems developed by AdnaGen have been used for the sensitive and specific analysis of CTC. Results: Case reports of 2 breast cancer patients demonstrate the successful detection of CTC for therapy monitoring purposes. The disappearance of CTC reflects therapy success. The patient that responded towards therapy was characterized by the disappearance of CTC from the first therapeutic unit (TU) onwards. In contrast, CTC remained detectable in the other patient during the whole therapy pointing to only limited therapeutic efficacy and a progressive disease. Furthermore, systematic changes in the expression profile of CTC in colorectal patients at different stages of disease could be observed. Whereas EGFR was expressed in 90% of the patients with CTC during primary disease the expression level decreased to 15% in CTC of metastatic patients. On the other hand the expression of CEA was low in CTC found after primary surgery (15%) and dominant in CTC of metastatic patients (80%). Conclusion: The analysis of CTC is a useful tool for therapy monitoring of breast cancer and colorectal cancer patients in the adjuvant and palliative situation. The molecular profiling of CTC may be used to identify therapeutic targets such as HER2 or EGFR for personalised treatment that is likely to have an important impact on the therapeutic efficacy of drugs like Herceptin® or Erbitux®