Comparison of Dako HercepTest and Ventana PATHWAY anti-HER2 (4B5) tests and their correlation with silver in situ hybridization in lung adenocarcinoma

BACKGROUND: Discordant results exist about the role of human epidermal growth factor receptor 2 (HER2) overexpression and/or HER2 amplification in lung adenocarcinoma. We aimed to compare the performance of HercepTest and PATHWAY anti-HER2 (4B5) by correlating immunohistochemistry (IHC) results with silver in situ hybridization (SISH) in adenocarcinoma lung specimens. METHODS: A total of 148 surgically resected adenocarcinoma lung specimens were included. RESULTS: HER2 overexpression was found in 7.4% patients for HercepTest Dako and in 2.7% patients for 4B5 antibody. The overall coincidence between these two types of antibodies equals 93.9%. The incidence of HER2 amplification in lung adenocarcinoma was 17.6%, of which in 2.7% of the cases high-grade amplification was present. HER2 amplification was present in 90.9% of patients with overexpression of HER2, obtained by using HercepTest Dako and 75% patients using 4B5 antibody. A significant correlation between overexpression of HER2 receptors obtained by HercepTest Dako and 4B5 antibody and HER2 amplification was shown. CONCLUSION: The research of the efficiency of targeted molecular therapies with an HER2 antibody may serve as a basis for the introduction of routine HER2 status determination in lung adenocarcinoma, dictating the need for the standardized protocol for HER2 status determination in such pathology.