The evolving role of HER2 evaluation for diagnosis and clinical decision making for breast and gastric adenocarcinoma

Abstract

Clinical laboratory testing for human epidermal growth factor receptor-2 (HER2) in patients with newly diagnosed breast and gastric cancer is critically important for therapeutic decisions about adjuvant treatment. The HER2 pathway is a major molecular driver of disease progression in a subset of these solid tumors and the results of HER2 testing determine which patients are likely to respond to an expanding variety of therapies that target this important biologic pathway. Given the significant clinical impact of these test results on patient management and adjuvant treatment decisions, standardization of the assay for HER2 and assured reliability of these results are critical. We review highlights of the clinical rationale that underlies HER2 testing for both breast and gastric carcinomas, and describe some of the challenges associated with ensuring accurate test results.

Key words::

• breast cancer
• gastric cancer
• gene amplification
• HER2
• immunohistochemistry
• in situ hybridization
• trastuzumab

Acknowledgment

The authors thank Mary Jackson for her assistance in the preparation of this manuscript.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.