58P - Concordance of local and central HER2 status in 1597 patients participating in German neoadjuvant breast cancer studies

Date 07 May 2015
Event IMPAKT 2015
Session Welcome reception and Poster Walk
Topics Breast Cancer
Pathology/Molecular Biology
Presenter Berit Pfitzner
Citation Annals of Oncology (2015) 26 (suppl_3): 15-24. 10.1093/annonc/mdv117
Authors B.M. Pfitzner1, S. Loibl2, J. Lindner3, P. Sinn4, B. Lederer2, S. Braun5, K.W. Schmid6, C. Denkert1, G. von Minckwitz2
  • 1Institute Of Pathology, Charité Universitätsmedizin Berlin, 10117 - Berlin/DE
  • 2Medicine And Research, German Breast Group, GBG Forschungs GmbH, 63263 - Neu-Isenburg/DE
  • 3Institute Of Pathology, Charité Universitätsmedizin Berlin, Berlin/DE
  • 4Institute Of Pathology, University Hospital Heidelberg, 69120 - Heidelberg/DE
  • 5Institute Of Pathology, Klinikum Offenbach GmbH, 63069 - Offenbach/DE
  • 6Institute Of Pathology, University Hospital Essen Westdeutsches Tumorzentrum, 45147 - Essen/DE

Abstract

Body

Introduction: In 2014, breast cancer was the most frequently diagnosed cancer in females. Human epidermal growth factor receptor 2 (HER2; also known as EGFR-related 2, ERBB2) is one of four known members of the EGFR family. About 18-25% of invasive human breast cancers show an ERBB2 amplification and overexpression. These tumors exhibit a more aggressive behavior. The humanized antibody mAb4D5 as well as the therapeutic antibody trastuzumab were evolved. Additionally, Trastuzumab emtansine (T-DM1) implies all capabilities of trastuzumab combined with an intensely potent cytotoxic agent. Therefore, determination of the true HER2 status is important. In this project, we investigated the hypothesis that the rate of discordance between central and local pathology decreased during the last years.

Methods: We compared the central and local HER2 status of five large neoadjuvant, multicenter breast cancer studies which randomized patients with primary invasive breast cancer between 2001 and 2013.

Results: 1597 patients with HER2 positive cancers were included. The discordance rate decreased from 52.4% in the GeparTrio trial to 8.4% in the GeparSepto trial (GeparQuattro: 25.4, GeparQuinto: 22.7, GeparSixto: 7.0). 62.6% of patients had hormone receptor positive, HER2 positive tumors. The discordance for HER2 in this subgroup decreased as follows: GeparTrio 58.8%, GeparQuattro: 30.8%, GeparQuinto: 29.2%, GeparSixto: 0%, GeparSepto: 9.2% In the remaining 37.4% of patients with hormone receptor negative, HER2 positive tumors, the discordance rate for HER2 decreased, too, except for GeparSixto: GeparTrio 37.9%, GeparQuattro: 18.9%, GeparQuinto: 13.9%, GeparSixto: 16.3%, GeparSepto 6.1%.

Conclusion: Our study demonstrates in a huge analysis of five neoadjuvant breast cancer studies a decrease of the discordance rate comparing the central and local HER2 status. This trend coincides with the implementation of ring tests and other quality control measures for HER2-testing in Germany.

Disclosure: All authors have declared no conflicts of interest.