Marked differences in the frequency of microsatellite instability in gastric cancer from different countries

OBJECTIVE: Previous studies have reported variable rates of microsatellite instability (MSI) in gastric cancer. We investigated the frequency of MSI in invasive gastric carcinoma of patients from three geographic regions. METHODS: Genomic DNA from gastric cancer and nontumor tissue from 22 Korean, 20 Colombian, and 26 U.S. patients was amplified with five microsatellite markers. RESULTS: MSI was more frequently seen in gastric cancer from Korea, affecting 50% of patients, in contrast with gastric cancers from the U.S. (7%) and Colombia (15%) (p = 0.003 and p = 0.03, respectively). MSI at one locus was significantly more frequent in gastric cancer from individuals \u3e65 yr (p = 0.01). MSI was similarly associated with both diffuse and intestinal types of gastric cancer. CONCLUSIONS: MSI affects the two major histological types of gastric cancer, and was more frequent in gastric cancer from Korea than in the other countries, suggesting that the relative importance of different pathways of gastric carcinogenesis may vary in diverse regions of the world