An analysis of HER-2/neu gene status in invasive ductal carcinomas using immunohistochemistry and fluorescence in situ hybridization

Abstract

Conclusion: Our found rate (11.9%) of HER-2/neu overexpression was lower than the rates reported in the literature, while our HER-2/neu gene amplification rate (28.8%) was compatible with the reported rates. HER-2/neu gene amplification was associated with tumor grade. Although high rates of concordance between HER-2/neu gene overexpression and amplification in cases with scores of 2+ and 3+ were obtained, the discordance rate in cases with a score of 1+ was higher than those of other studies. The discordance rate in cases with a score of 1+ and positive lymph node status was higher than that of the total study group. According to our results, a score of 1+ indicated less conclusive immunostaining for the HER-2/neu gene, and cases with scores of 1+ in the metastatic group had a higher rate of HER-2/neu gene amplification than that of the total study group. Our results show that FISH analysis for HER-2/neu gene status should be performed in cases with an immunostaining score of 1+, especially in those cases with positive axillary lymph node results.