摘要目的：了解HER2免疫组织化学结果不确定的乳腺癌荧光原位杂交（FISH）阳性和阴性两组患者的原位mRNA表达特征，探索mRNA原位杂交（ RNAscope ）用于乳腺癌组织HER2检测的潜在可行性。方法收集北京协和医院2010年6月至2013年6月间手术获得的69例乳腺浸润性导管癌组织HER2免疫组织化学结果不确定（ IHC 2＋）的石蜡标本，并制作组织芯片，分别采用FISH和RNAscope技术检测其HER2基因状态和原位mRNA表达，计数100个癌细胞，按mRNA表达量从低到高的5个等级（0、1、2、3、4分）判读mRNA结果。分析FISH阳性和阴性两组患者HER2 mRNA的表达特征。结果在69例标本中，FISH阳性共23例，其中RNAscope 16例（70％，16／23）4分、6例（26％，6／23）3分、1例（4％，1／23）2分。96％的 HER2 FISH 阳性标本为原位 mRNA 高表达（ RNAscope≥3分），RNAscope 4分的标本全部为FISH阳性。在FISH阴性的46例标本中，RNAscope 17例（37％，17／46）3分、25例（54％，25／46）2分、4例（9％，4／46）1分。结论根据原位mRNA表达结果，可将IHC 2＋乳腺癌病例进一步分类，其中以RNAscope 4分为mRNA高表达的判读标准可能成为确认IHC 2＋结果的检测技术。 HER2原位mRNA检测可作为提示乳腺癌HER2基因扩增和蛋白质表达的候选检测手段，具有潜在的临床应用价值。

abstractsObjective To investigate in situ mRNA expression of HER 2 oncogene in breast cancers with equivocal immunohistochemical results , and to explore the potential feasibility of RNAscope technique in evaluating HER2 status in breast cancers .Methods Sixty-nine FFPE samples of invasive ductal breast cancer with equivocal HER 2 immunohistochemistry results ( IHC 2+) were collected from surgical excisions from Peking Union Medical College Hospital between June 2010 and June 2013.HER2 status and in situ mRNA expression were tested by fluorescence in situ hybridization ( FISH) and RNAscope respectively using tissue microarray constructed from tumor paraffin blocks .The results of HER2 mRNA expression were scored 0 to 4 ( from low to high levels ) according to mRNA expression in 100 cancer cells .HER2 mRNA expression was evaluated in two groups of patients , with positive and negative FISH results .Results Twenty-three of the 69 samples were FISH positive, including 16 samples that were scored 4 by RNAscope (70%,16/23), 6 samples were scored 3 ( 26%,6/23 ) and one sample was scored 2 ( 4%,1/23 ) .High in situ mRNA expression (score 4 or 3) were observed in 96%of HER2 FISH positive samples.All of samples that were scored 4 by RNAscope were FISH positive .Forty-six samples were FISH negative , including 17 samples that were scored 3 by RNAscope (37%,17/46), 25 samples were scored 2 (54%,25/46), and 4 samples were scored 1 (9%,4/46).Conclusions Breast cancer with HER2 IHC 2 +could be further classified according to in situ mRNA expression status .Among them, RNAscope score of 4 could be one of the interpretation criteria for re-testing IHC 2+samples.In situ detection of HER2 mRNA may be an additional candidate method of confirmation for HER 2 gene amplification or protein overexpression , and has potential clinical utility.