Human epidermal growth factor receptor 2 (HER2) gene status and overexpression, occurring in ~ 13.6% of primary breast cancers, is essential for identifying patients likely to benefit from biological treatment. In this method of evaluation study, we tested and compared the HER2 gene–protein assay (GPA) with routine HER2 immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). The GPA was evaluated using 67 formalin‐fixed paraffin‐embedded (FFPE) HER2 equivoval IHC (2+) breast cancer tissue samples. Overall, agreement between GPA silver in situ hybridization (SISH) and FISH was 91.9% (57/62). Regression analysis revealed slightly higher, but non‐significant difference in HER2/chromosome enumeration probe 17 (CEP17) ratio for GPA as compared to FISH (p = 0.074). Intraclass correlation coefficients (ICCs) of 0.94 and Spearman´s rank correlation coefficients of 0.93 (p < 0.0001) for FISH and GPA SISH suggested strong inter‐observer association for methods with one observer counting on average 0.23 significant higher for GPA SISH (p = 0.014). Intra‐observer IHC method reproducibility was 52.6% (κ = 0.3122, p = 0.004) and 79.7% (κ = 0.6428, p = 0.9197), suggesting fair significant and substantial non‐significant difference between tests for reviewers. Inter‐observer reproducibility for IHC methods was 53%. While inter‐observer reproducibility for experienced IHC interpretation suggested significant differences (κ = 0.3636, p = 0.0332), unexperienced interpretation of IHC GPA suggested fair non‐significant difference between reviewers (κ = 0.3101, p = 0.0747). Using FISH as reference, the diagnostic indices for GPA SISH were as follows: sensitivity 100%, specificity 95% and accuracy 92%. Inaccuracy between tests was in 80% of cases due to ISH categorization as equivocal by one of the methods. IHC results highlight that it may be beneficial with a method for simultaneously visualization of HER2 gene and protein status.

中文翻译：

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乳腺癌患者HER2状态分析准确性的评估：HER2 GPA与HER2 IHC和HER2 FISH的比较。

在约13.6％的原发性乳腺癌中发生的人类表皮生长因子受体2（HER2）基因状态和过度表达对于确定可能受益于生物治疗的患者至关重要。在这种评估研究方法中，我们测试了HER2基因蛋白测定（GPA）并将其与常规HER2免疫组织化学（IHC）和荧光原位杂交（FISH）进行了比较。使用67个福尔马林固定石蜡包埋（FFPE）HER2等价IHC（2+）乳腺癌组织样本评估了GPA。总体而言，GPA银原位杂交（SISH）和FISH之间的一致性为91.9％（57/62）。回归分析显示HER2 /染色体计数探针17（CEP17GPA与FISH的比率（p = 0.074）。FISH和GPA SISH的类内相关系数（ICC）为0.94，Spearman秩相关系数为0.93（p <0.0001），表明方法的观察者之间具有很强的关联性，一位观察者的GPA SISH平均平均高0.23（p = 0.014）。观察者内部IHC方法的重现性分别为52.6％（κ= 0.3122，p = 0.004）和79.7％（κ= 0.6428，p = 0.9197），表明对于审阅者而言，测试之间的显着性和非显着性差异。IHC方法的观察者间可重复性为53％。观察者之间对经验丰富的IHC解释的可重复性表明存在显着差异（κ= 0.3636，p = 0.0332），而对IHC GPA的未经验解释则表明审稿人之间存在显着的非显着差异（κ= 0.3101，p = 0.0747）。以FISH为参考，GPA SISH的诊断指标如下：敏感性为100％，特异性为95％，准确性为92％。由于ISH将其中一种方法归类为模棱两可，因此在80％的情况下，测试之间的不准确性。IHC结果突出表明，同时显示HER2基因和蛋白质状态的方法可能有益。