Microsatellite instability in oral cancer

Abstract

Generalized genomic instability, detected as somatic changes in allele sizes at microsatellite loci in tumors compared to peripheral lymphocyte DNA, is a recently recognized mechanism of mutation in cancer. Such instability results from the Somatic loss of DNA mismatch repair capability. Germ‐line mutations at DNA mismatch repair loci confer susceptibility to colon cancer in hereditary non‐polyposis colorectal cancer. Somatic loss of DNA mismatch repair has been reported in a large variety of other tumor types. Our goal was to determine the frequency of microsatellite instability in a large series of oral tumors. Out of 91 tumors analyzed for microsatellite instability, 6 (7%) showed microsatellite instability. Instability was observed at multiple loci with a range of 50‐74% of loci affected. Alterations include both increase (74%) and decrease (26%) in allele sizes. The proportion of alleles affected ranged from 30‐58% of all alleles. Our data suggest that somatic genomic instability plays a role in the pathogenesis of a small subset of oral tumors.