Correlation between HER2/neu protein overexpression on Immunohistochemistry and Fluorescent in Situ Hybridization (FISH) in breast carcinoma: Problems in developing countries

Abstract

Objective: To correlate the results of HER2/neu protein overexpression on immunohistochemistry (IHC) and gene amplification on fluorescence in situ hybridization (FISH) and to document the problems faced in performing FISH procedure. Methods: This was an observational retrospective study covering five years from January 1st, 2015 - December 31st, 2019 at Histopathology Department of Shifa International Hospital (SIH), Islamabad. All cases of breast cancer that underwent florescence in situ hybridization (FISH) were retrieved. Correlation between HER2/neu overexpression on IHC and its amplification on FISH was analyzed. Problems in application of FISH were recorded. Results: Out of 451 cases submitted for HER2/neu testing by FISH, 68 cases (15%) were rejected. Gene amplification was seen in 139 (36.29%) cases. Total cases with HER2/neu IHC score of 2+ were 330 cases and out of which gene amplification was seen in 98 cases (29.69%) whereas 93.1% (41/44) 3+ IHC cases were amplified. Poor fixation, inadequate amount of tumor with crushing artefacts and dye application to the biopsy fragments were causes of sample rejection. Conclusions: Her2/neu amplification was seen in most Her2/neu 3+ cases and approximately one-third of Her2neu 2+ cases. Proper fixation, adequate biopsy material with standardized processing is required to yield useful results on FISH. doi: https://doi.org/10.12669/pjms.39.6.6704 How to cite this: Mukhtar Z, Faisal A, Mudassir G, Mamoon N. Correlation between HER2/neu protein overexpression on Immunohistochemistry and Fluorescent in Situ Hybridization (FISH) in breast carcinoma: Problems in developing countries. Pak J Med Sci. 2023;39(6):---------.  doi: https://doi.org/10.12669/pjms.39.6.6704 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.