[Gene expression analysis in breast cancer. A new diagnostic tool in pathology].

Molecular biomarker analysis is increasingly being used as a basis for individualized therapy selection. In breast cancer established standard biomarkers are hormone receptors, HER2 and if indicated Ki67. In particular for hormone receptor positive, HER2 negative tumors, gene expression analysis provides additional information on proliferation and hormone receptor signalling. The results of the gene expression tests can be used to identify patients with a very good prognosis under an exclusive endocrine therapy. This group of patients can then be treated without conventional chemotherapy. The EndoPredict assay was validated in two large cohorts from clinical studies of the Austrian breast cancer study group (ABCSG). Furthermore, using a round robin test, the test method was established in several German institutes of molecular pathology. The EndoPredict assay can be carried out in local institutes of pathology and offers additional information to existing standard prognostic parameters.