PT  - JOURNAL ARTICLE
AU  - Rafaniello-Raviele, Paola
AU  - Betella, Ilaria
AU  - Rappa, Alessandra
AU  - Vacirca, Davide
AU  - Tolva, Gianluca
AU  - Guerrieri-Gonzaga, Aliana
AU  - Bertario, Lucio
AU  - Barberis, Massimo
AU  - Bonanni, Bernardo
AU  - Marabelli, Monica
TI  - Microsatellite instability evaluation: which test to use for endometrial cancer?
AID  - 10.1136/jclinpath-2021-207723
DP  - 2023 Jan 01
TA  - Journal of Clinical Pathology
PG  - 29--33
VI  - 76
IP  - 1
4099  - http://jcp.bmj.com/content/76/1/29.short
4100  - http://jcp.bmj.com/content/76/1/29.full
SO  - J Clin Pathol2023 Jan 01; 76
AB  - Aims Analysis of microsatellite instability (MSI) is strongly recommended in endometrial cancer (EC) and colorectal cancer to screen for Lynch syndrome, to predict prognosis and to determine optimal treatment and follow-up. In a large monoinstitutional series of ECs, we evaluated the reliability and accuracy of Idylla assay, a rapid, fully automated system to detect MSI, and we compared its performance with two routine reference methods.Methods We evaluated MSI status in 174 formalin-fixed, paraffin-embedded EC tissue samples using immunohistochemistry (IHC) for mismatch repair (MMR) proteins and Idylla assay. Samples with discordant or equivocal results were analysed with a third technique, the Promega MSI kit.Results Idylla MSI assay and IHC were highly concordant (overall agreement: 154/170=90.59%, 95% CI 85.26% to 94.12%). However, in four samples, MMR-IHC staining was equivocal; moreover, 16 cases showed discordant results, that is, MMR deficient using IHC and microsatellite stable using Idylla. These 20 samples were reanalysed using the MSI-Promega kit, which showed the same results of Idylla assay in 18/20 cases (overall agreement: 90%, 95% CI 69.90% to 97.21%).Conclusions Our results suggest that IHC is an efficient method to determine MMR status in ECs. However, the Idylla MSI assay is a rapid and reliable tool to define MSI status, and it could represent a valuable alternative to conventional MSI-PCR methods.All data relevant to the study are included in the article.