The significance of mismatch repair genes in gastric cancer.

BACKGROUND: Microsatellite instability (MSI) is a form of genetic instability characterized by new alleles not present in the normal genotype. This mutation occurs by altered DNA mismatch repair (MMR) genes. Studies of limited numbers of patients have reported conflicting results regarding the association of the MSI phenotype with gastric cancer. This study aims to evaluate the clinical significance of mismatch repair genes in gastric cancer.
MATERIALS AND METHODS: We studied 156 gastric cancer patients who underwent gastrectomy from March 2010 to February 2011 in our hospital. Mismatch repair status was determined by the immunohistochemical analysis of human MutL Homolog 1 (hMLH1) and human MutS Homolog 2 (hMSH2) expression.
RESULTS: Seventeen (10.9%) cases did not express hMLH1 but all cases expressed hMSH2. In univariate analyses, the expression of hMLH1 was associated with age, nodal status, and Lauren's classification. In multivariate analyses, there was no statistically significant association between the loss of hMLH1 expression and selected clinical parameters.
CONCLUSION: The expression of hMLH1 was associated with age, nodal status, and Lauren's classification. Our results suggest that MMR gene abnormalities play an important role in the tumorigenesis of patients demonstrating gastric cancer.