No abstract

To clarify field cancerization in the stomach by genetic alterations, we studied 83 cases of intestinal-type gastric cancer (GC) and paired intestinal metaplasia (IM) distant from GC and 39 cases of chronic gastritis with IM (CG-IM) for genetic instability (GIN). Microsatellite instability (MSI) and loss of heterozygosity (LOH) were evaluated at 5 microsatellite loci. The incidence of GIN was 21% (8/39) in CG-IM, 48% (40/83) in GC-IM, and 65% (54/83) in GC and showed a significant difference among these 3 categories. By tumor location, MSI showed the highest incidence in GC and GC-IM with the tumor located in the upper third of the stomach. GIN in GC and GC-IM significantly increased with the progression of tumor invasion from mucosal to advanced cancer. GIN, especially LOH, was more frequently detected in cases with vs without lymphatic or vascular invasion and lymph node involvement in GC and GC-IM. The GIN of GC and GC-IM was significantly similar in relation to clinicopathologic features. Biologic detection of GIN in IM may be a surrogate marker for GC risk and for clinical evaluation of malignant potential. The condition is consistent with the hypothesis of field cancerization in the stomach.

Summary Background There is little evidence of changes in genetic variations in gastric intestinal metaplasia (GIM) after the eradication of Helicobacter pylori (H. pylori). Aim To investigate the effects of H. pylori eradication on genetic GIM variability in patients with and without gastric cancer in a one‐year prospective study. Methods We analysed microsatellite instability (MSI) and loss of heterozygosity (LOH) in GIM. Subjects included Gr. A (n = 39): chronic gastritis, and Gr. B (n = 53): intestinal‐type early gastric cancer patients who underwent endoscopic mucosal resection (n = 25) and surgical resection (n = 28). Results The frequency of incidence of MSI in GIM was 10.3% and 28.3% for Gr. A and Gr. B, respectively. Gr. B showed a significantly (p = 0.03) higher incidence rate than Gr. A for MSI, but not for LOH. The frequency of MSI declined in both groups post‐eradication, and patients that were positive for MSI before treatment were negative after H. pylori eradication. Unfortunately, however, GIM scores did not decline significantly post‐treatment for either group. Conclusions MSI in GIM may be associated with gastric carcinogenesis. H. pylori eradication reduced MSI during the one‐year post‐treatment period, although no histological improvement in GIM was observed. These changes in MSI may explain the decrease in gastric cancer incidence after the eradication of H. pylori.

SUMMARY BackgroundThere is little evidence of changes in genetic variations in gastric intestinal metaplasia (GIM) after the eradication of Helicobacter pylori (H. pylori).

K-ras mutations in IM do not always play a role in gastric carcinogenesis but cell kinetics, especially apoptosis, in IM may contribute to it. There are early events in K-ras mutations which are influenced by H pylori infection; some mutations may also be selected by eradication. These unstable K-ras mutations in IM may be related to lymphocyte infiltration caused by H pylori infection.