Comparison of Alu-PCR, microsatellite instability, and immunohistochemical analyses in finding features characteristic for hereditary nonpolyposis colorectal cancer

Abstract

Purpose: To evaluate and compare alterations detected by Alu-PCR, microsatellite instability (MI), and absence of hMLH1 and hMSH2 protein expression measured by immunohistochemical (IHC) analyses as features characteristic of hereditary nonpolyposis colorectal cancer (HNPCC). Methods: Alu-PCR, MI, and IHC analyses were performed in two groups of patients: (A) HNPCC diagnosed definitively or with high probability (11 patients); (B) sporadic late-onset colorectal cancers (15 patients). Results: Quantitative alterations recorded by Alu-PCR were not characteristic for Lynch syndrome, occurring more frequently in sporadic late-onset CRC (73% in group B vs 45% in group A). Qualitative changes (occurrence of additional peaks or shifts) have been found to be associated with HNPCC – with odds ratio (OR) 2.4, specificity ~70% and sensitivity ~55%. Findings in MI and IHC analyses have been recognized as features more characteristic of HNPCC suggesting Lynch syndrome with OR 4.8, specificity ~80%, sensitivity ~55% (MI) and OR 8.0, specificity ~93%, sensitivity ~36% (IHC). Conclusion: Molecular techniques allowing identification of patients with a high probability of having HNPCC include IHC and MI analyses. Our results suggest that their replacement by Alu-PCR analysis in diagnosis of HNPCC is not justified.