Discordance between immunochemistry of mismatch repair proteins and molecular testing of microsatellite instability in colorectal cancer.
ESMO Open
; 6(3): 100120, 2021 06.
Article
em En
| MEDLINE
| ID: mdl-33930657
ABSTRACT
BACKGROUND:
DNA mismatch repair system deficiency (dMMR) is found in 15% of colorectal cancers (CRCs). Two methods are used to determine dMMR, immunohistochemistry (IHC) of MMR proteins and molecular testing of microsatellite instability (MSI). Only studies with a low number of patients have reported rates of discordance between these two methods, ranging from 1% to 10%. MATERIALS ANDMETHODS:
Overall, 3228 consecutive patients with CRCs from two centers were included. Molecular testing was carried out using the Pentaplex panel and IHC evaluated four (MLH1, MSH2, MSH6, and PMS2; cohort 1; n = 1085) or two MMR proteins (MLH1 and MSH2; cohort 2; n = 2143). The primary endpoint was the rate of discordance between MSI and MMR IHC tests.RESULTS:
Fifty-one discordant cases (1.6%) were initially observed. Twenty-nine out of 51 discordant cases were related to IHC misclassifications. In cohort 1, after re-reading IHC and/or carrying out new IHC, 16 discordant cases were reclassified as nondiscordant. In cohort 2, after the addition of MSH6/PMS2 IHC and re-examination, 13 were reclassified as nondiscordant. In addition, 10 misclassifications of molecular tests were identified. Finally, only 12 discordant cases (0.4%) remained 5 were proficient MMR/MSI and 7 were dMMR/microsatellite stable.CONCLUSIONS:
Our study confirmed the high degree of concordance between MSI and MMR IHC tests. Discordant cases must be reviewed, and if needed, tests must be repeated and analyzed by an expert team.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Neoplasias Colorretais
/
Instabilidade de Microssatélites
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
ESMO Open
Ano de publicação:
2021
Tipo de documento:
Article