The Effectiveness of Clinical Guidelines in the Diagnosis of Lynch Syndrome Compared to Microsatellite Instability and Immunohistochemistry Analyses in Southern Thailand

Abstract

Objective: This study aims to assess the accuracy of Amsterdam II criteria (AMII) and Revised Bethesda Guidelines (RBG) compared to molecular tests in Thai patients.Material and Methods: One hundred eighty-one patients were enrolled. Demographic data and pathological features and locations of tumors were recorded. Family history of the patients was reviewed by AMII and RBG. Tissue samples were collected and molecular testing was tested by microsatellite instability (MSI) analysis and immunohistochemistry (IHC). Statistical analysis was used to estimate the sensitivity and specificity of AMII and RBG compared to molecular testing.Results: Of the patients, 2.8% fulfilled the AMII criteria and 28.1% met the RBG criteria. Molecular testing showed 16.57% and 13.8% of the samples lost at least 1 out of 4 mismatch repair (MMR) proteins in the IHC test. In addition, 10.5% of patients had both microsatellite instability high (MSI-H) and loss of protein MMR expression. The sensitivity and specificity of AMII were 6.7% and 98.0%, respectively, while for the RBG they were 70.0% and 82.1%, respectively.Conclusion: The present study suggests that for patients who complete the AMII, doctors should be highly suspicious of Lynch syndrome, due to its high specificity. The RBG is useful for screening for Lynch syndrome and the selection of individuals for further molecular testing.