Bartels S, Grote I, Wagner M, Boog J, Schipper E, Reineke‐Plaass T, Kreipe H, Lehmann U. Concordance in detection of microsatellite instability by PCR and NGS in routinely processed tumor specimens of several cancer types.
Cancer Med 2023;
12:16707-16715. [PMID:
37376830 PMCID:
PMC10501280 DOI:
10.1002/cam4.6293]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 06/14/2023] [Accepted: 06/15/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND
Microsatellite instability (MSI) occurs in several cancer types and is commonly used for prognosis and as a predictive biomarker for immune checkpoint therapy.
METHODS
We analyzed n = 263 formalin-fixed paraffin-embedded (FFPE) tumor specimens (127 colorectal cancer (CRC), 55 endometrial cancer (EC), 33 stomach adenocarcinoma (STAD), and 48 solid tumor specimens of other tumor types) with a capillary electrophoresis based multiplex monomorphic marker MSI-PCR panel and an amplicon-based NGS assay for microsatellite instability (MSI+). In total, n = 103 (39.2%) cases with a known defect of the DNA mismatch repair system (dMMR), determined by a loss in protein expression of MSH2/MSH6 (n = 48, 46.6%) or MLH1/PMS2 (n = 55, 53.4%), were selected. Cases with an isolated loss of MSH6 or PMS2 were excluded.
RESULTS
The overall sensitivity and specificity of the NGS assay in comparison with the MSI-PCR were 92.2% and 98.8%. With CRC cases a nearly optimal concordance was reached (sensitivity 98.1% and specificity 100.0%). Whereas EC cases only show a sensitivity of 88.6% and a specificity of 95.2%, caused by several cases with instability in less than five monomorphic markers, which could be difficult to analyze by NGS (subtle MSI+ phenotype).
CONCLUSIONS
MSI analysis of FFPE DNA by NGS is feasible and the results show a high concordance in comparison with the monomorphic marker MSI-PCR. However, cases with a subtle MSI+ phenotype, most frequently manifest in EC, have a risk of a false-negative result by NGS and should be preferentially analyzed by capillary electrophoresis.
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