Specificity of HercepTest in Determining HER-2/neu Status of Breast Cancers Using the United States Food and Drug Administration–Approved Scoring System

Authors

null

Timothy W. Jacobs

Timothy W. Jacobs, Allen M. Gown, Hadi Yaziji, Melissa J. Barnes, Stuart J. Schnitt

Preview

PURPOSE: To evaluate the specificity of the HercepTest for Immunoenzymatic Staining (Dako Corp, Carpinteria, CA) for determining HER-2/neu protein expression in breast cancer.

MATERIALS AND METHODS: Forty-eight invasive breast cancers previously found to be HER-2/neu–negative by two different immunohistochemical (IHC) assays and not amplified for the HER-2/neu gene by fluorescence in situ hybridization were studied using the HercepTest kit. HercepTest was performed according to the manufacturer's guidelines, and the results were scored on a 0 to 3+ scale using the United States Food and Drug Administration (FDA)–approved grading system. In this system, cases scored as 2+ or 3+ are considered HER-2/neu–positive.

RESULTS: Among these 48 cases, the IHC score using the FDA-approved scoring system was 0 in four cases (8.3%), 1+ in 16 (33.3%), 2+ in 21 (43.8%), and 3+ in seven (14.6%). Therefore, 58.4% of these cases were categorized as HER-2/neu–positive, and the specificity of the HercepTest kit for HER-2/neu expression was 41.6%. However, with the use of a modified scoring system that took into account the level of staining of nonneoplastic epithelium, the specificity increased to 93.2%.

CONCLUSION: Our results indicate that the HercepTest kit, when used in accordance with the manufacturer's guidelines and the FDA-approved scoring system, results in a large proportion of breast cancers being categorized as positive for HER-2/neu protein expression and that many of these seem to be false-positives. Consideration of the level of staining of nonneoplastic epithelium resulted in improved specificity. The current FDA-approved scoring system for HercepTest results should be reevaluated before its widespread use in clinical practice.

View Full Journal Article

Journal Details

DOI

10.1200/JCO.1999.17.7.1983

Published Date

July 1, 1999

Similar Journals

First Author: Andrew D. Seidman

Publish Date: May 15, 2001

First Author: Lyndsay N. Harris

Publish Date: Mar 15, 2001

Journal

Journal of Clinical Oncology

HER-2 and Topoisomerase II As Predictors of Response to Chemotherapy

First Author: Kathleen I. Pritchard

Publish Date: Feb 10, 2008