Supplementary Material for: Comparison of HER2 Expression in Primary Tumor and Disseminated Tumor Cells in the Bone Marrow of Breast Cancer Patients Rack B. Zombirt E. Trapp E. Jückstock J. Andergassen U. Neugebauer J. Kost B. Weissenbacher T. Jeschke U. Schindlbeck C. 10.6084/m9.figshare.5129206.v1 https://karger.figshare.com/articles/dataset/Supplementary_Material_for_Comparison_of_HER2_Expression_in_Primary_Tumor_and_Disseminated_Tumor_Cells_in_the_Bone_Marrow_of_Breast_Cancer_Patients/5129206 <b><i>Objective:</i></b> The aim of this study was to measure the human epidermal growth factor receptor 2 (HER2) status of disseminated tumor cells (DTCs) from bone marrow (BM) aspirates and to assess correspondence or discrepancy with the primary tumor. <b><i>Methods:</i></b> DTCs were isolated from the BM of 156 breast cancer patients. Cytokeratin-positive DTCs were further analyzed by the chromogenic in situ hybridization method to detect HER2 gene amplification. <b><i>Results:</i></b> A significant correlation (p = 0.021) was found between the HER2 status of DTCs and the primary tumors. Sixty-one (68.5%) patients had a corresponding status. However, a shift of phenotype between primary tumor and DTCs was found in the remaining patients. <b><i>Conclusion:</i></b> This study showed a significant grade of discordance of the HER2 status between primary tumors and DTCs in the BM of a relevant subgroup of patients. Detection of HER2 amplification on DTCs could therefore help to better stratify patients for a more tailored therapy, since they would benefit from a HER2-targeted therapy. 2016-03-04 00:00:00 Breast cancer Circulating tumor cells Disseminated tumor cells Minimal residual disease HER2 Bone marrow HER2-targeting agent