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目的目前最常用的筛查结直肠癌DNA错配修复基因缺失的方法是免疫组化检测错配修复(MMR)基因相关蛋白的表达,以及基于PCR检测多个微卫星位点判断有否微卫星不稳定(MSI)这2种方法,本研究主要目的是比较这二种检测之间的一致性,并对分子病理室作室内质量控制。方法收集2014年8月至2015年10月湖北省肿瘤医院结直肠癌368例手术切除标本,免疫组化常规检测癌组织MLH1,PMS2,MSH2及MSH6这4种蛋白的表达。免疫组化显示任一蛋白完全缺失,判读为MMR蛋白缺失(d MMR);如癌细胞4个MMR有多少不等的核着色,判读为MMR无缺失(p MMR)。选取其中的65例行PCR-毛细管电泳法检测MSI,其中28例为p MMR,37例为d MMR。然后对这65例组织用PCR毛细管电泳法检测Bethesda推荐的5个微卫星位点。比对这65例患者上述二种检测结果之间的一致性,并分析、整理其临床病理特征。结果 368例结直肠癌中有37例免疫组化结果为d MMR中,其余331例为p MMR。37例中剔除2例后对其中35例行毛细管PCR法检测,显示高频MSI者32例,微卫星稳定(MSS)者3例。选取331例中的28例行PCR检测,显示MSS者27例,MSI-H者1例。免疫组化法检测的敏感度和特异性分别为97.0%和90.0%,PCR检测结果的敏感度和特异性分别为91.4%和96.4%;二者总的一致性为93.7%。伴MSI的结直肠癌原发灶以右半结肠最多见(占48.6%),病理形态以低分化腺癌伴淋巴细胞浸润和粘液分泌最常见,病理TNM分期以Ⅱ期和Ⅲ期为主。结论免疫组化检测MMR蛋白和基于PCR的毛细管电泳法检测MSI二者的一致性高,其中免疫组化法可以作为临床初筛结直肠癌微卫星不稳定性的一种经济而便捷的方法,值得推广。
OBJECTIVE: The most commonly used screening method for screening DNA mismatch repair genes in colorectal cancer is immunohistochemistry to detect the expression of mismatch repair (MMR) gene-related proteins and to determine whether there are microsatellites based on PCR detection of multiple microsatellite loci Instability (MSI), the main purpose of this study is to compare the consistency between the two tests and to control the molecular pathology room for indoor quality control. Methods 368 cases of colorectal cancer in Hubei Provincial Cancer Hospital from August 2014 to October 2015 were collected for surgical resection. The expressions of MLH1, PMS2, MSH2 and MSH6 were detected by immunohistochemistry. Immunohistochemistry showed a complete deletion of any protein, interpreted as a lack of MMR protein (d MMR); for example, how many nuclear stains were found in the 4 MMRs of cancer cells, interpreted as MMR loss-free (p MMR). Sixty-five patients were selected for PCR-capillary electrophoresis for detection of MSI, of which 28 were p MMR and 37 were d MMR. The 65 microsatellites were then tested for Bethesda-recommended 5 microsatellite loci using PCR capillary electrophoresis. The 65 patients were compared between the two test results of the consistency, and analysis, sorting out the clinical and pathological features. RESULTS: Thirty-seven of the 368 colorectal cancers had an immunohistochemical result of d MMR and the remaining 331 were p MMR. Thirty-five cases were detected by capillary PCR after removing two cases in 37 cases, showing that there were 32 cases of high-frequency MSI and 3 cases of microsatellite stable (MSS). Twenty-eight out of 331 cases were detected by PCR, which showed 27 cases of MSS and 1 case of MSI-H. The sensitivity and specificity of immunohistochemistry were 97.0% and 90.0%, respectively. The sensitivity and specificity of PCR assay were 91.4% and 96.4% respectively. The overall consistency was 93.7%. The primary colorectal cancer with MSI was the most common in the right colon (48.6%). The most common pathological findings were poorly differentiated adenocarcinoma with lymphocytic infiltration and mucus secretion. The pathological TNM stages were mainly stage Ⅱ and Ⅲ. Conclusion The consistency of immunohistochemical detection of MMR protein and PCR-based capillary electrophoresis for the detection of MSI is high. Immunohistochemistry can be used as an economical and convenient method to screen microsatellite instability of colorectal cancer clinically. Worth promoting.