肠癌微卫星状态检测方法的比较

Comparison of two detection methods for microsatellite status of colorectal cancer

目的:探索PCR法与IHC法对微卫星状态判断的差异性与一致性。方法:收集南京鼓楼医院病理科2014年6月至2015年12月病理诊断明确的大肠癌手术切除标本485例,所有标本的微卫星状态通过检测癌组织及正常组织中BAT25、BAT26、D5S346、D2S123及D17S250等5个标准位点的突变状态确定,并同时采用IHC法检测标本癌组织中MLH1、MSH2、MSH6和PMS2等DNA错配修复基因蛋白的表达,对比两种检测结果之间的一致性。结果:PCR法共检测到MSI状态39例,包括30例MSI-H和9例MSI-L,MSS状态446例,MSI占所有病例的8.04%,其中MSI-H的比率为6.19%。485例患者的免疫组化检测结果显示蛋白缺失(dMMR)者61例,蛋白不缺失(pMMR)者424例,d MMR占所有病例的12.58%。IHC法检测的灵敏度和特异度分别为86.67%和92.31%,两种方法检测微卫星状态的符合率为91.96%。结论:IHC法和PCR法检测微卫星状态具有较高的一致性,IHC法经济、便捷,更便于临床推广,当IHC法检测4种修复蛋白均无缺失时,则可以诊断为MSS/MSI-L,无需进一步行PCR,而当发现有任一修复蛋白有缺失时,则需行PCR检测进一步判定是否存在微卫星不稳定状态。我们的这一结论,将为临床工作节省大量的时间与成本。

Objective：To search the differences between the PCR and IHC in the diagnosis of microsatellite status.Methods：This study collected 485 colorectal cancer cases with clear pathological diagnosis.Microsatellite status of all cases has been determined by detecting the BAT25,BAT26,D5S346,D2S123 and D17S250 mutation status of cancer tissues and normal tissues.The expression of DNA mismatch repair （MMR） genes of MLH1,MSH2,MSH6 and PMS2 have been detected by IHC simultaneously.Results：In the 485 patients with colorectal cancer,MSI status was detected in 39 cases,including 30 cases of MSI-H and 9 cases of MSI-L.The incidence of MSI was 8.04%,and the incidence of MSI-H was 6.19%.IHC analyses were performed on 485 cases of colorectal cancer,among which 61 cases were dMMR and 424 cases were pMMR.The incidence of dMMR was 12.58%.The sensitivity and specificity of IHC were 86.67% and 92.31%,the coincidence rate of the two methods for detecting microsatellite status was 91.96%.Conclusion：The results of IHC are accorded with PCR.Compared with PCR,IHC is more economical,convenient and easier for clinical promotion.When one case exhibites all mismatch repair protein positive expression by IHC,we can diagnose MSS/MSI-L,without further PCR detection,but when any repair protein is found to be missing,PCR detection is required to determine whether there is microsatellite instability.This result will save a lot of time and cost for clinical work.