PT  - JOURNAL ARTICLE
AU  - Kullmann, Friederike
AU  - Strissel, Pamela L
AU  - Strick, Reiner
AU  - Stoehr, Robert
AU  - Eckstein, Markus
AU  - Bertz, Simone
AU  - Wullich, Bernd
AU  - Sikic, Danijel
AU  - Wach, Sven
AU  - Taubert, Helge
AU  - Olbert, Peter
AU  - Heers, Hendrik
AU  - Lara, María Fernanda
AU  - Macias, Maria Luisa
AU  - Matas-Rico, Elisa
AU  - Lozano, Maria José
AU  - Prieto, Daniel
AU  - Hierro, Isabel
AU  - van Doeveren, Thomas
AU  - Bieche, Ivan
AU  - Masliah-Planchon, Julien
AU  - Beaurepere, Romane
AU  - Boormans, Joost L
AU  - Allory, Yves
AU  - Herrera-Imbroda, Bernardo
AU  - Hartmann, Arndt
AU  - Weyerer, Veronika
TI  - Frequency of microsatellite instability (MSI) in upper tract urothelial carcinoma: comparison of the Bethesda panel and the Idylla MSI assay in a consecutively collected, multi-institutional cohort
AID  - 10.1136/jclinpath-2021-207855
DP  - 2023 Feb 01
TA  - Journal of Clinical Pathology
PG  - 126--132
VI  - 76
IP  - 2
4099  - http://jcp.bmj.com/content/76/2/126.short
4100  - http://jcp.bmj.com/content/76/2/126.full
SO  - J Clin Pathol2023 Feb 01; 76
AB  - Aims Upper tract urothelial carcinoma (UTUC) is a rare malignancy with a poor prognosis which occurs sporadically or in few cases results from a genetic disorder called Lynch syndrome. Recently, examination of microsatellite instability (MSI) has gained importance as a biomarker: MSI tumours are associated with a better response to immunomodulative therapies. Limited data are known about the prevalence of MSI in UTUC. New detection methods using the fully automated Idylla MSI Assay facilitate analysis of increased patient numbers.Methods We investigated the frequency of MSI in a multi-institutional cohort of 243 consecutively collected UTUC samples using standard methodology (Bethesda panel), along with immunohistochemistry of mismatch repair (MMR) proteins. The same tumour cohort was retested using the Idylla MSI Assay by Biocartis.Results Using standard methodology, 230/243 tumours were detected as microsatellite stable (MSS), 4/243 tumours as MSI and 9/243 samples as invalid. In comparison, the Idylla MSI Assay identified four additional tumours as MSS, equalling 234/243 tumours; 4/243 were classified as MSI and only 5/243 cases as invalid. At the immunohistochemical level, MSI results were supported in all available cases with a loss in MMR proteins. The overall concordance between the standard and the Idylla MSI Assay was 98.35%. Time to result differed between 3 hours for Idylla MSI Assay and 2 days with the standard methodology.Conclusion Our data indicate a low incidence rate of MSI tumours in patients with UTUC. Furthermore, our findings highlight that Idylla MSI Assay can be applied as an alternative method of MSI analysis for UTUC.Data are available upon reasonable request.