Detection of HER-2 mRNA and protein expression in breast cancer tissues by using chromogenic in situ hybridization and immunohistochemistry methods / 肿瘤

ABSTRACT

Objective: To detect human epidermal growth factor receptor-2 (HER-2) gene amplification and protein expression by using chromosome in situ hybridization (CISH) method and compare the results with immunohistochemical assays (IHC). Methods: We assessed the amplification status of HER-2 gene with CISH method in 145 cases of breast cancer tissues. Fourteen out of 145 specimens have been tested by fluorescence in situ hybridization (FISH). HER-2 gene amplification and protein expression in the 145 cases of breast cancer tissues were tested by IHC methods. We retrospectively compared the detection results among the three methods and analyzed the correlation of HER-2 expression with various high-risk factors of breast cancer such as pathological grade, lymph node metastasis, menopausal status, and the expression of estrogen receptor (ER)/progesterone receptor (PR). Results: Based on CISH assay, non-amplification of HER-2 gene was observed in 71 cases (50.0%), low-amplification was detected in 11 cases (7.6%), and high-amplification was assessed in 63 cases (43.4%). The concordance rate between FISH (n = 14) and CISH was 100.0% (14/14). The concordance rate between IHC and CISH was 84.8% (n = 145, P 90%) was in agreement with its protein expression. However, the amplification rate of HER-2 gene was only 61.1% IHC + + cases. Both CISH and IHC detection demonstrated that expression of ER/PR was negatively related with the expression of HER-2. The amplification rate of HER-2 gene was significantly higher in ER/PR-negative patients that that in ER/ PR-positive patients (CISH 68.3% vs 38.8%, P < 0.01; IHC 71.7% vs 48.2%, P < 0.01). The amplification status of HER-2 gene had no correlation with tumor pathological grade, auxiliary lymph node metastasis, and menopausal status. Conclusions: CISH for HER-2 detection is easy to handle and has high accuracy. It could replace FISH to further confirm the status of HER-2 gene in IHC + + cases. HER-2 is negatively related with ER/PR expression but has no relationship with other risk factors such as pathological grade, auxiliary lymph node metastasis, and menopausal status. HER-2 should be tested independently.