The primary aim of this prospective-explorative phase 0 study is to investigate the influence of adjuvant radiotherapy in patients with non-metastatic breast cancer on the circulating epithelial tumor cells (CETCs) in the peripheral blood and their immunohistochemical characteristics in younger high risk (premenopausal) versus older low risk (postmenopausal) patients. In addition, the immunophenotype will be determined using peripheral venous blood mononuclear cells (PBMCs) at different time points during the course of therapy and correlated with the results of CETC analysis. The aim of the study is to identify prognostic and predictive biomarkers for early stage breast cancer patients. No therapeutic consequences will be derived.
For this purpose, the phenotype and molecular biological profile of CETC will be investigated and compared with the corresponding characteristics of the primary tumor in order to assign the tumor cells detected in the peripheral blood to the primary tumor. In this context, the number of tumor-infiltrating lymphocytes (TILs) will be correlated with circulating tumor cells and immunophenotype.
Another goal is the characterization of individually isolated CETC by RT-PCR. The expression of selected marker genes involved in metastatic processes will be investigated during the course of therapy and compared with that of the primary tumor to identify therapy-associated changes. The in vitro cultivation of so-called tumor spheres and their characterization as a sign of a therapy-resistant phenotype is a secondary objective of the study.
