Evaluation of HER2 gene amplification status in invasive breast cancer patients by Fluorescence in Situ Hybridization analysis and its correlation with clinical features

Abstract

Precise assessment of HER2 gene status as an important biomarker plays a significant role in identifying the eligible patients for Trastuzumab therapy and determining their clinical outcomes. In this study, the researchers assigned HER2 amplification status in invasive breast cancer specimens by Fluorescence in Situ Hybridization (FISH) and determined its association with other clinical features. Formalin-fixed paraffin embedded tumor tissue specimens of 46 patients with invasive breast cancer were collected from November 2011 till May 2012. HER2status was evaluated by FISH. The Zytolight SPEC HER2/CEN17 dual color probe kit was applied for assessment of HER2status. HER2 gene amplification was defined as HER2/CEP17 ratio>2.2.The association between HER2status and clinical features like tumor grade, tumor type, tumor size, axillary lymph node involvement and age of patient was done using Chi squared test at the 0.05 level of significance (p value). Amplification of HER2 gene was detected in twelve cases (26%). On statistical analysis HER2status showed correlation with tumor grade (p=0.02).There was no correlation between HER2status and tumor type, tumor size, lymph node status and age of patients. The results of this study are consonant with the findings of other studies about the presence of HER2 gene amplification in invasive breast cancer. Statistical analysis showed patients with HER2 amplified gene have tumors with higher grade. In these patients the probability of increased proliferation and metastasis is high therefore evaluation of HER2 gene amplification status in breast cancer patients specially in high grade tumor with an accurate method such as FISH is essential