Table of Contents
Pathology Research International
Volume 2011, Article ID 903202, 16 pages
Review Article

Testing for HER2 in Breast Cancer: A Continuing Evolution

Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA

Received 15 September 2010; Accepted 22 October 2010

Academic Editor: Rohit Bhargava

Copyright © 2011 Sejal Shah and Beiyun Chen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Human epidermal growth factor receptor 2 (HER2) is an important prognostic and predictive factor in breast cancer. HER2 is overexpressed in approximately 15%–20% of invasive breast carcinomas and is associated with earlier recurrence, shortened disease free survival, and poor prognosis. Trastuzumab (Herceptin) a “humanized” monoclonal antibody targets the extracellular domain of HER2 and is widely used in the management of HER2 positive breast cancers. Accurate assessment of HER2 is thus critical in the management of breast cancer. The aim of this paper is to present a comprehensive review of HER2 with reference to its discovery and biology, clinical significance, prognostic value, targeted therapy, current and new testing modalities, and the interpretation guidelines and pitfalls.