Turning over a New Leaf : precision medicine in oncology guided by circulating tumor cell counts and characteristics

Many new treatments have been put on the market over the past decades, but have been proven to be effective in only 20-50% of the patients. To improve the prognosis of patients with cancer and in order to keep cancer care affordable, it will be important to select effective treatments for individual patients up-front. To avoid the risks and discomfort of tissue biopsies as well as to account for heterogeneity between tumor locations, blood sampling for circulating tumor cells may aid as a liquid biopsy.

In this thesis, the possibilities and clinical relevance of the use of a liquid biopsy by the characterization of CTCs for patients with metastatic breast, prostate and colorectal cancer are described. The studies in this thesis focus on the predictive value of CTCs and to what extent they resemble metastatic lesions versus primary tumors.