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Concordance between central and local laboratory HER2 testing from a community-based clinical study
Josina C Reddy1, James D Reimann, Steven M Anderson
1Genentech, Inc, South San Francisco, CA 94080, USA. josina@gene.com
Clinical Breast Cancer
|June 28, 2006
Summary
Accurate HER2 testing is crucial for identifying women with HER2-overexpressing breast cancer who will benefit from trastuzumab. Central laboratory testing, using both IHC and FISH, yields the most reliable results for this critical biomarker.
Area of Science:
- Oncology
- Biomarker Testing
- Clinical Pathology
Background:
- HER2-overexpressing breast cancer presents a poor prognosis.
- Trastuzumab significantly improves survival and reduces relapse in early-stage and metastatic breast cancer.
- Accurate HER2 testing is essential for patient selection for trastuzumab therapy.
Purpose of the Study:
- To evaluate the accuracy of HER2 testing methods and locations.
- To determine the impact of laboratory type on HER2 test concordance.
Main Methods:
- Prospective, phase IV study (HER-First) of first-line trastuzumab/taxane therapy.
- Retesting of all tumor specimens using HER2 IHC and FISH at a central, high-volume laboratory.
Main Results:
- Concordance between local and central HER2 IHC testing varied, with lowest agreement for IHC 2+ samples (26%).
- 33% of local IHC 2+ samples were FISH-positive at the central laboratory.
- Higher concordance between HER2 IHC and FISH was observed when both tests were performed centrally.
Conclusions:
- Accurate HER2 testing is critical for identifying patients eligible for trastuzumab.
- HER2 testing performed at a high-volume reference laboratory demonstrates superior accuracy.