Detection of human epidermal growth factor receptor 2 gene in invasive breast cancer by fluorescence in situ hybridization and research of its association with tumor characteristics

To investigate the concordance of detecting human epidermal growth factor receptor 2 (HER-2) status of patients with invasive breast cancer by fluorescence in situ hybridization (FISH) for gene amplification and immunohistochemistry (IHC) for protein overexpression and to evaluate the association between tumour characteristics and HER-2 gene amplification.The HER-2 status was evaluated in 41 invasive ductal breast carcinomas by both FISH and IHC. The associations between HER-2 gene amplification and other clinicopathological factors, tumour grade, estrogen receptor (ER), tumor emboli, lymph node status, were evaluated using the chi-square test.HER-2 amplifications by FISH were seen in 15 patients, including 8 IHC+++ patients (88.89%, 8/9 of all+++ cases), 6 IHC++ patients (42.68%, 6/14 of all++ cases), 1 IHC+ patient (8.33%, 1/12 of all+ cases) and none IHC negative patient (0%, 0/6 of all negative cases). ER negative or weak positive breast cancers were more often HER-2 FISH positive than ER strong positive cancers (P=0.018). HER-2 amplifications were more often negative in tumor emboli negative or lymph node negative patients than in tumor emboli positive or lymph node positive patients (P=0.000, P=0.025). There was no statistical difference in HER-2 gene amplification among different grades of tumors(P=0.095).HER-2 amplification in breast cancer can be determined by FISH accurately. ER is negatively associated with HER-2 amplification, whereas tumor emboli and lymph node status are positively associated with HER-2.PubMed02199-2034