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This retrospective study assessed concordance in MMR status and MSI evaluation using immunohistochemistry (IHC), polymerase chain reaction (PCR), and next-generation sequencing (NGS) in 534 CRC patients, and investigated drivers of discordant cases.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/comparison-of-immunohistochemistry-pcr-and-ngs-for-the-evaluation-of-mismatch-repair-deficiency-and-microsatellite-instability-in-colorectal-cancer-a-retrospective-study/356943/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/comparison-of-immunohistochemistry-pcr-and-ngs-for-the-evaluation-of-mismatch-repair-deficiency-and-microsatellite-instability-in-colorectal-cancer-a-retrospective-study/356943.png","ImageObject",300,407,{"name":92,"@type":93},"eBook King","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-09-27","2026-09-23",true,{"@type":102,"interactionType":103,"userInteractionCount":19},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What three methods were compared for MSI/MMR evaluation in colorectal cancer?","Question",{"text":112,"@type":113},"The study compared immunohistochemistry (IHC) for MMR protein expression with polymerase chain reaction (PCR) and next-generation sequencing (NGS) for MSI assessment in 534 colorectal cancer patients.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How did IHC, PCR, and NGS classify cases in the results?",{"text":117,"@type":113},"IHC classified 7.3% (39/534) as deficient mismatch repair (dMMR), PCR classified 7.5% (40/534) as MSI-H, and NGS classified 7.3% (39/534) as MSI-H.",{"name":119,"@type":110,"acceptedAnswer":120},"What explains discordant results between the methods?",{"text":121,"@type":113},"Discordant cases (0.9%, five cases) were attributed mainly to assay-specific limitations, tumor heterogeneity, technical or pre-analytical issues, and biological variability.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},356943,1790246927,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":19,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":44,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":144},962088006270,"https://ap-avatar.wpscdn.com/davatar_085a072bc5b1113ac321206ff7593b45","Wang et al. Diagnostic Pathology (2026) 21:49 [https://doi.org/10.1186/s13000-026-01788-6](https://doi.org/10.1186/s13000-026-01788-6)  \nDiagnostic Pathology  \nRESEARCH Open Access  \nComparison of immunohistochemistry, PCR,  and NGS for the evaluation of mismatch  \nrepair deficiency and microsatellite instability in colorectal cancer: a retrospective study  \nLei Wang1, Yuan Hu1, Huazun Yuan1, Na Yu1, Li Xiao1* and Jingjing Jin1*  \nAbstract  \nBackground Microsatellite instability (MSI) and mismatch repair (MMR) deficiency serves as a critical predictive biomarker for the efficacy of immune checkpoint inhibitors (ICIs) in colorectal cancer (CRC) . However, discrepancies among detection methods may lead to inconsistent results, which may contribute to ICIs resistance. This study aimed to evaluate the concordance of MMR status and MSI assessment across three commonly used methods and to explore factors underlying discordant cases.  \nMethods We retrospectively analyzed MSI status in 534 CRC patients using three detection methods: immunohistochemistry (IHC) for MMR protein expression, and polymerase chain reaction (PCR) and next-generation sequencing (NGS) for MSI status assessment. Concordance between methods was measured using Kappa statistics, and discordant cases were further investigated.  \nResults Among the 534 cases, 7 . 3%(39/534) were classified as deficient mismatch repair (dMMR) by IHC, 7. 5%(40/534) as MSI-H by PCR, and 7. 3%(39/534) as MSI-H by NGS. The highest concordance was observed between PCRand NGS (Kappa = 0 . 986), followed by NGS and IHC (Kappa = 0 . 943), and PCR and IHC (Kappa = 0 . 930) . Discordant results occurred in five cases (0 . 9%), primarily attributable to assay-specific limitations, tumor heterogeneity, technical or pre-analytical issues, and biological variability.  \nConclusion IHC, PCR, and NGS showed high overall concordance in MSI and MMR assessment. The small number of discordant cases highlights the inherent limitations of individual methods. While single-method testing is generally reliable, multi-platform evaluation may provide additional insights in diagnostically challenging or borderline cases. Keywords Microsatellite instability, Mismatch repair protein, Colorectal cancer, Immunohistochemistry, Polymerase chain reaction, Next-generation Sequencing  \n*Correspondence:  \nLi Xiao [fangjx0207@foxmail.com](fangjx0207@foxmail.com)[ ](fangjx0207@foxmail.com)Jingjing Jin [flyingfish312@126.com](flyingfish312@126.com)  \n1Department of Pathology, Affiliated Huadong Hospital of Fudan University, Shanghai 200040, China  \n© The Author(s) 2026. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit [http://creati](http://creati)[vecommons.org/licenses/by-nc-nd/4.0/](vecommons.org/licenses/by-nc-nd/4.0/.)[.](vecommons.org/licenses/by-nc-nd/4.0/.)  \nWang et al. Diagnostic Pathology (2026) 21:49  \nIntroduction  \nColorectal cancer (CRC) is the third most prevalent malignancy worldwide, ranking third in incidence and second in mortality among all cancers [1]. Although the incidence of CRC is higher in devel","cbCait3b6oDetpE8","https://ap.wps.com/l/cbCait3b6oDetpE8","pdf",2247753,"English","# Abstract\n# Methods\n# Results\n# Conclusion\n# Introduction","[{\"question\":\"What three methods were compared for MSI/MMR evaluation in colorectal cancer?\",\"answer\":\"The study compared immunohistochemistry (IHC) for MMR protein expression with polymerase chain reaction (PCR) and next-generation sequencing (NGS) for MSI assessment in 534 colorectal cancer patients.\"},{\"question\":\"How did IHC, PCR, and NGS classify cases in the results?\",\"answer\":\"IHC classified 7.3% (39/534) as deficient mismatch repair (dMMR), PCR classified 7.5% (40/534) as MSI-H, and NGS classified 7.3% (39/534) as MSI-H.\"},{\"question\":\"What explains discordant results between the methods?\",\"answer\":\"Discordant cases (0.9%, five cases) were attributed mainly to assay-specific limitations, tumor heterogeneity, technical or pre-analytical issues, and biological variability.\"}]","Comparison of immunohistochemistry, PCR, and NGS for the evaluation of mismatch repair deficiency and microsatellite instability in colorectal cancer - a retrospective study | PDF",1790128375,23]