HER2/neu Testing In 432 Consecutive Breast Cancer Cases using FISH and IHC - A Comparative Study

Area of Science:

• Oncology
• Molecular Diagnostics
• Biomarker Analysis

Background:

• Trastuzumab therapy significantly improves outcomes for HER-2/neu amplified breast cancer.
• Accurate HER-2/neu status determination is crucial for patient stratification.
• Fluorescence In Situ Hybridization (FISH) and Immunohistochemistry (IHC) are standard diagnostic methods.

Purpose of the Study:

• To evaluate the concordance rate between FISH and IHC for HER-2/neu status in breast cancer.
• To assess the reliability of these methods in clinical practice.

Main Methods:

• Analysis of archival paraffin-embedded tumor tissues from 450 breast cancer patients.
• HER-2/neu status assessed using both FISH and IHC assays.

Main Results:

• A highly significant concordance was observed between FISH and IHC for HER-2/neu status.
• Inverse associations were found between HER-2/neu amplification and Estrogen/Progesterone Receptor (ER/PR) expression.

Conclusions:

• While IHC shows good concordance with FISH, its subjective nature limits its use as a gold standard.
• FISH should be the definitive method for confirming gene amplification, especially when IHC results are equivocal.