Kannangara D K S, Lokuhetty M D S, Subasinghe D, Gunawardene Y I N S, Dassanayake R S
Post Graduate Institute of Medicine, University of Colombo, Colombo, Sri Lanka.
Department of Pathology, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka.
Indian J Gastroenterol. 2019 Aug;38(4):317-324. doi: 10.1007/s12664-019-00955-6. Epub 2019 Aug 10.
Human epidermal growth factor receptor 2 (HER2) protein overexpression and/or HER2 gene amplification are/is linked to a dismal outcome of gastric carcinoma (GCa). Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) are key methods to identify patients for HER2 targeted therapy. Drawbacks of both the methods warrant novel tests. Hence, we evaluated the value of quantitative real-time polymerase chain reaction (qPCR) as an alternative test method, relative to IHC to detect HER2 status of GCa and to find relationship between these results with demographic/clinicopathological data.
Twenty GCa patients with known IHC HER2 scores were evaluated. qPCR was performed for the HER2 gene and amyloid precursor protein (reference gene) in formalin-fixed paraffin-embedded GCa tissue. Cycle threshold values (Ct) were analyzed using the Pfaffl method to detect HER2 gene amplification.
HER2 positivity rates by IHC and qPCR were 20% and 35%, respectively. The sensitivity and specificity of qPCR were 67% and 76%, respectively, relative to IHC. qPCR results were reproducible. The diagnostic consistency between IHC and qPCR (κ = 0.146) was slightly agreeable (0.01 < k < 0.20), with a 65% concordance. Based on McNemar's test, there was no significant difference between the results of the two tests. IHC HER2 protein expression had relationship with the tumor (TNM) stage and Lauren histological type (p < 0.05). Positive HER2 gene expression by qPCR showed relationship with depth of invasion, lymph node involvement, and degree of differentiation (p < 0.05).
Cost-effective qPCR could serve as an alternative test method for detection of HER2 status of GCa. Both HER2 overexpression by IHC and gene amplification by qPCR are associated with adverse clinicopathological features.
人表皮生长因子受体2（HER2）蛋白过表达和/或HER2基因扩增与胃癌（GCa）的不良预后相关。免疫组织化学（IHC）和荧光原位杂交（FISH）是识别适合HER2靶向治疗患者的关键方法。这两种方法的缺点促使人们寻求新的检测方法。因此，我们评估了定量实时聚合酶链反应（qPCR）作为一种替代检测方法的价值，相对于IHC检测GCa的HER2状态，并找出这些结果与人口统计学/临床病理数据之间的关系。
对20例已知IHC HER2评分的GCa患者进行评估。在福尔马林固定石蜡包埋的GCa组织中对HER2基因和淀粉样前体蛋白（参考基因）进行qPCR。使用Pfaffl方法分析循环阈值（Ct）以检测HER2基因扩增。
IHC和qPCR检测的HER2阳性率分别为20%和35%。相对于IHC，qPCR的敏感性和特异性分别为67%和76%。qPCR结果具有可重复性。IHC和qPCR之间的诊断一致性（κ = 0.146）为轻度一致（0.01 < k < 0.20），一致性为65%。基于McNemar检验，两种检测结果之间无显著差异。IHC HER2蛋白表达与肿瘤（TNM）分期和Lauren组织学类型有关（p < 0.05）。qPCR检测HER2基因阳性表达与浸润深度、淋巴结受累及分化程度有关（p < 0.05）。
经济高效的qPCR可作为检测GCa患者HER2状态的替代检测方法。IHC检测的HER2过表达和qPCR检测的基因扩增均与不良临床病理特征相关。
