Determination of HER-2/neu by Chromogenic in Situ Hybridization on Borderline (2+) Immunohistochemistry Cases in Carcinoma Breast

Objective: To determine the HER-2/neu status by chromogenic in situ hybridization (CISH) on tissue specimenswith a borderline (2+) immunohistochemistry (IHC) score in carcinoma breast by a descriptive, cross-sectionalstudy in the Histopathology Department, Armed Forces Institute of Pathology (AFIP), Rawalpindi from Jun 2008to Dec 2009.
Methods: Tissue block specimens from 50 consecutive patients having HER-2/neu score of borderline(2+) on IHC assay were tested for HER-2/neu gene amplification by CISH. Mean and standard deviation werecalculated for quantitative variables like age and HER-2/neu gene copy signal/clusters by using SPSS version14. Frequencies and percentages were also calculated for qualitative variables like type of carcinoma and resultsof HER-2/neu by CISH (amplified/nonamplified).
Results: HER-2/neu gene amplification by CISH was foundin 10 (20%) out of 50 patients with borderline (2+) IHC score. All CISH amplified cases belonged to invasiveductal carcinoma type. No significant correlation was noted between type of carcinoma and HER-2/neu geneamplification.
Conclusion: Chromogenic in situ hybridization (CISH) is a practical, cost-effective and reliablemethod for analysis of HER-2/neu borderline (2+) cases which may be candidates for Herceptin therapy.