Abstract: Objective To compare the consistence of fluorescence in situ hybridization （FISH） with immunohistochemistry （IHC） in detecting human epidermalgrowth factor receptor-2 （HER-2） status in infiltrating ductal breast carcinoma. Methods The expression of C-erbB-2 protein and HER2 gene amplification of 346 cases with infiltrating ductal breast carcinoma was tested by IHC and FISH methods， and the results were compared.
ResultsAmong 346 specimens of infiltrating ductal breast carcinoma， HER-2 gene amplification was present in 145 cases （41.9％） by FISH， and absent in 201 cases （58.1％）. IHC detection of C-erbB-2 protein results showed that （-） in 7 cases， （+） in 30 cases， （++） in 227 cases and （+++） in 82 cases. According to the guidline for the detection of HER2 in breast cancer， （-） and （+） were negative results， （+++） was positive results， and （++） was uncertain. The positive rate of C-erbB-2 protein in 346 specimens was 23.7％ （82／346）. There were 7 cases with negative expression of C-erbB-2 by IHC， among which HER-2 gene amplification was absent in 7 cases with the coincidence rate of 100.0％. Five among 30 showed a negative result of （+） by IHC， but was positive in FISH， and the coincidence rate was 833％. In the 227 cases with a positive result of （++） by IHC， the amplification of HER2 gene was present in 65 cases， with the coincidence rate of 28.6％.The positive result of （+++） was demonstrate in 82 cases， among whom the HER-2 gene amplification was detected in 75 cases， with the coincidence rate of 915％. The consistency of these two methods was very good in the cases with negative （-／+） or positive （+++） expression of CerbB2. The total concordance rate of HER2 between IHC and FISH trials was 899％ with the Kappa value of 0.768（P＜0.001）. HER-2 gene amplification was not related to age， tumor size， histological grade and lymph node metastasis （P＞0.05）. Conclusion HER-2 expression of infiltrating ductal breast carcinoma detected by IHC was highly consistent with FISH detection. IHC is a preliminary method to detect HER-2 status in infiltrating ductal breast carcinoma. However， in the cases with positive （++） expression of C-erbB-2， FISH should be performed to detect the gene amplification of HER-2.