Can Microsatellite Status of Colorectal Cancer Be Reliably Assessed after Neoadjuvant Therapy?

Clinical Cancer Research : an Official Journal of the American Association for Cancer Research
Jennifer B GoldsteinEduardo Vilar

Abstract

Purpose: Determination of microsatellite instability (MSI) by PCR is the gold standard; however, IHC of mismatch repair (MMR) proteins is frequently performed instead. The reliability of these methods on postneoadjuvant therapy specimens is unknown. We examined the effect of neoadjuvant therapy on MSI results by PCR and IHC.Experimental design: A total of 239 colorectal cancers resected after neoadjuvant therapy were assessed for MSI with PCR and IHC. PCR and IHC results for matched paired pre- and posttreatment specimens were compared. In parallel, 2 isogenic cell lines conditioned for MMR functioning and 2 different patient-derived xenografts (PDXs) were exposed to chemotherapy, radiation, or both. We also examined whether establishment of PDXs induced MSI changes in 5 tumors. IHC and MSI were tested after treatment to assess for changes.Results: We identified paired pre- and posttreatment specimens for 37 patients: 2 with PCR only, 34 with IHC only, and 1 with both. All 3 patients with PCR had microsatellite stable pre- and posttreatment specimens. Of the 35 patients with IHC, 30 had intact MMR proteins in pre- and posttreatment specimens, 1 had equivocal MLH1 staining in the pretreatment and loss in the posttreatment specim...Continue Reading

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Citations

Feb 28, 2018·CA: a Cancer Journal for Clinicians·Patrick M BolandC Richard Boland
Dec 1, 2018·International Journal of Cancer. Journal International Du Cancer·Georg Martin HaagMatthias Kloor
Mar 1, 2019·Colorectal Disease : the Official Journal of the Association of Coloproctology of Great Britain and Ireland·A CavazzaK J Monahan
Oct 2, 2019·Cold Spring Harbor Perspectives in Medicine·Andrea Forman, Jilliane Sotelo
Oct 12, 2018·Endoscopy International Open·Ferga C GleesonLizhi Zhang
Dec 9, 2020·Critical Reviews in Oncology/hematology·Zhenli DiaoJinming Li

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