Background Gastric cancer incidence is much higher in Eastern Asian than Western and South East Asian countries. Helicobacter pylori(H.pylori) infection is not only the one cause that play an important role in the development of gastric cancer but also,producing the nitroso carcinogenic compounds by bacteria,high salt intake,and the presence of pathogenic strains of H.pylori might be other causes . Interleukin-8(IL-8) is one of the chemokines,which express in gastric mucosal tissues,and induced by local production of proinflammatory cytokines. Cyclo-oxygenase 2(COX-2 ) is induced during inflammations,and high level of COX-2 expression is related to the carcinogenesis.Both Japanese and Thais had high prevalence of H.pylori infection,but the gastric cancer incidence in Thais is lower than in Japanese by ratio of 1:12.According to suspicious differences in gastric carcinogenesis between Japanese and Thais,H.pylori infection and mucosal defence of the stomach including bile reflux,and exogenous factors might be related to the risk of gastric carcinogenesis are studied as racial difference of host factor in details Method2003 - 2008,we performed upper gastrointestinal endoscopy in 242 Japanese(38 had endoscopic treatment for gastric cancer ,94 had distal gastrectomy,110 with other conditions) and 62 Thais(10 with gastric cancer and 52 with other conditions). H.pylori infection were diagnosed by pathologic study . The IL-8,COX-2 mRNA expression levels were detected by RT-PCR Results The IL-8 expression level in Japanese and COX-2 expression level in Thais were higher in HP+ve than HP-ve cases (p<0.05). In Thais,the COX-2 level was higher in cancer cases(4184+/-3392)than non-cancer cases(719+/-216)(p=0.025).In cancer cases,the IL-8 and COX-2 levels were higher in Thais(0.82+/-0.52, 4184+/-3392)than Japanese(0.20+/-0.05,72+/-20) (p<0.05).In distal gastrectomy cases,the IL-8 level was higher in HP+ve than HP-ve cases(p<0.05). The COX-2 level in gastric mucosa after BillothII(171+/-61)>Endoscopic mucosal resection(113+/-78)> BillothI(51+/-21) ConclusionsH.pylori infection is one of key factors to elevate degree of inflammations in gastric mucosa,related to difference in gastric mucosal defence among nations especially in chronic atrophic gastritis condition.Background of gastric mucosa in stomach with cancer of Thais can produce the high expression level of COX-2.This results might be caused by exogenous factors such as local cigarette smoking or diets,which can aggravate the production of proinflammatory cytokine in gastric mucosa. These factors might be related to the development of gastric cancer in Thais.In Japanese,bile reflux and the persistence of H.pylori infection after distal gastrectomy can elevate degree of inflammations in stomach.This conditions might be increased risk of gastric cancer more than other conditions in stomach

Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 1859.

100th AACR Annual Meeting-- Apr 18-22, 2009; Denver, CO