This article is part of a series on HER2 therapy, edited by Mark Pegram.

Review

HER-2 therapy. HER-2/neu diagnostics in breast cancer

Walter P Carney¹ , Kim Leitzel², Suhail Ali³, Rainer Neumann⁴ and Allan Lipton²

¹Oncogene Science, Siemens Medical Solutions Diagnostics, Rogers Street, Cambridge, Massachusetts 02142, USA

²Penn Street University, Hershey Medical Center, University Drive, Hershey, Pennsylvania, USA

³Lebanon VA Medical Center, Lincoln Ave, Lebanon, Pennsylvania 17042, USA

⁴Siemens Medical Solutions DX, Siemensstrasse, D-35463 Fernwald, Germany

author email corresponding author email

Breast Cancer Research 2007, 9:207doi:10.1186/bcr1664

Published:	4 June 2007

Abstract

HER-2/neu status of the primary breast cancer (PBC) is determined by immunohistochemistry and fluorescent in situ hybridization. Because of a variety of technical factors, however, the PBC may not accurately reflect the metastatic tumor in terms of HER-2/neu status. Recently published guidelines recommend that tumors be defined as HER-2/neu positive if 30% or more of the cells are 3+. Circulating levels of the HER-2 extracellular domain can be measured in serum using a test cleared by the US Food and Drug Administration, and increased serum HER-2/neu levels to above 15 ng/ml can reflect tumor progression. Studies comparing tissue HER-2/neu status of the PBC and HER-2/neu levels above 15 ng/ml in metastatic breast cancer patients are also reviewed.