BACKGROUND: Although there have been some reports on microsatellite alterations in gastric cancer, findings are inconsistent regarding the associations between histological classification and microsatellite instability (MSI). In the present study, we attempted to determine whether Lauren's histological subtypes are related with MSI status. METHODS: Paraffin-embedded tissue samples from 14 diffuse-type and 14 intestinal-type gastric adenocarcinomas were matched up according to patient gender and age. Mononucleotide markers (BAT25 and BAT26) and dinucleotide markers (D2S123, D5S346, and D17S250) were used for MSI analyses. Microsatellite genotypes were categorized in terms of high MSI incidence (MSI-H, > 30% positive marker) or low MSI incidence (MSI-L, < 30% positive marker). Losses of hMLH1 and hMSH2 protein expression were immunohistochemically studied. RESULTS: MSI-H was observed in 11 cases (78%) of the 14 intestinal-type cases as compared to 3 (21%) of the 14 diffuse-type cases (p=0.007). In MSI-H tumors, 10 cases (71%) showed losses of hMLH1 protein expression, while 2 cases (14%) in MSI-L tumors showed losses of hMLH1 protein expression (p=0.006). CONCLUSION: MSI-H tumors are more frequently found in intestinal-type gastric cancer, which suggests the possibility that there are different pathogenic pathways in gastric carcinogenesis according to histologic type.
Adenocarcinoma/epidemiology/*genetics/pathology ; Aged ; Base Pair Mismatch/*genetics ; Comparative Study ; Female ; Gene Expression Regulation, Neoplastic ; Genotype ; Humans ; Incidence ; Korea/epidemiology ; Male ; Microsatellite Repeats/*genetics ; Neoplasm Proteins/genetics ; Nuclear Proteins/genetics ; Polymerase Chain Reaction ; RNA, Messenger/genetics ; Retrospective Studies ; Stomach Neoplasms/epidemiology/*genetics/pathology

BACKGROUND/AIMS: To identify the risk factors for metachronous gastric neoplasms in patients who underwent an endoscopic resection of a gastric neoplasm. METHODS: We prospectively collected clinicopathologic data and measured the methylation levels of HAND1, THBD, APC, and MOS in the gastric mucosa by methylation-specific real-time polymerase chain reaction in patients who underwent endoscopic resection of gastric neoplasms. RESULTS: A total of 257 patients with gastric neoplasms (113 low-grade dysplasias, 25 high-grade dysplasias, and 119 early gastric cancers) were enrolled. Metachronous gastric neoplasm developed in 7.4% of patients during a mean follow-up of 52 months. The 5-year cumulative incidence of metachronous gastric neoplasm was 4.8%. Multivariate analysis showed that moderate/severe corpus intestinal metaplasia and family history of gastric cancer were independent risk factors for metachronous gastric neoplasm development; the hazard ratios were 4.12 (95% confidence interval [CI], 1.23 to 13.87; p=0.022) and 3.52 (95% CI, 1.09 to 11.40; p=0.036), respectively. The methylation level of MOS was significantly elevated in patients with metachronous gastric neoplasms compared age- and sex-matched patients without metachronous gastric neoplasms (p=0.020). CONCLUSIONS: In patients who underwent endoscopic resection of gastric neoplasms, moderate/severe corpus intestinal metaplasia and a family history of gastric cancer were independent risk factors for metachronous gastric neoplasm, and MOS was significantly hypermethylated in patients with metachronous gastric neoplasms.
Aged ; Basic Helix-Loop-Helix Transcription Factors/genetics ; DNA Methylation ; Female ; Gastrectomy/methods ; Genes, APC/physiology ; Genes, mos/genetics ; Humans ; Incidence ; Male ; Middle Aged ; Multivariate Analysis ; Neoplasms, Second Primary/epidemiology/*genetics/pathology ; Proportional Hazards Models ; Risk Factors ; Stomach Neoplasms/genetics/*pathology/surgery ; Thrombomodulin/genetics