Comparison between fluorescence in situ hybridization and immunohistochemistry in detection of expression of human epidermal growth factor receptor 2 in breast cancer

Objective To investigate the relationship between human epidermal growth factor receptor 2 (HER-2) gene amplification, the expression of HER-2 protein and the clinical characteristics in invasive breast cancer. Methods 105 patients with invasive breast cancer were examined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). The correlation between expression of HER-2 protein and the gene amplification of HER-2 was compared, and their relationship with clinicopathologic features was analyzed. Results 105 patients with invasive breast cancer included 35 cases of HER-2 gene amplification. The coincidence rates of HER-2 protein 0 and+ (negative),++ (uncertainty),+++ (positive) and FISH detection of HER-2 gene amplification were 94.5% (17/18), 23.5% (16/68) and 94.7% (18/19) respectively. HER-2 gene amplification was associated with estrogen receptor, progesterone receptor expression and lymph node metastasis (all P 0.05). Conclusions The prognosis of invasive breast cancer is correlated with the amplification of HER-2 gene. Patients with HER-2 protein negative and positive can be selectively confirmed by FISH; patients with HER-2 protein uncertainty should routinely use FISH to detect HER-2 gene amplification status, which could provide data for the clinical treatment and prognosis judgement. Key words: Breast neoplasm; Receptor, epidermal growth factor; In situ hybridization, fluorescence; Immunohistochemistry