hOGG1 exon7 polymorphism and gastric cancer in case-control studies of Japanese Brazilians and non-Japanese Brazilians

Polymorphism of hOGG1 may be capable of serving as a genetic marker for ind ividual susceptibility to various cancers because of its role in the repair of oxyradical DNA damage. We examined the distribution of the hOGG1 Ser326 Cys polymorphism and its presumed correlation with gastric cancer risk in t wo case-control studies of different ethnic groups in Sao Paulo, Brazil. Po tentially eligible Japanese (JB) and non-Japanese Brazilian (NJB) case subj ects were defined as patients with newly diagnosed malignant neoplasms of t he stomach in 13 hospitals in Sao Paulo. Ninety-six JBs and 236 NJBs were a dopted as subjects. Two controls were matched for each JB case, and one con trol for each NJB case. The subjects were interviewed using a questionnaire and their blood samples were collected. A significant difference in the di stribution of this polymorphism between the two ethnic groups was observed (chi (2) = 58.3, P < 0.01). The mutant type (Ser/Cys or Cys/Cys) was predom inant (approximately 65%) in the JBs, but was only present in approximately 40% of the NJBs. Logistic regression analysis showed no significant increa sed risk for either the Ser/Cys or Cys/Cys type in either group. The odds r atios of the Cys allele for gastric cancer were 1.01 (95% confidence interv al (CI): 0.52-1.93) in the JBs and 0.85 (95% CI: 0.57-1.26) in the NJBs. In the NJBs, a significant increased risk of smoking was shown only in the Se r/Ser type, and no increased risk was shown in the genotypes with the Cys a llele. However, no statistically significant interactions were observed wit h smoking or other possible confounding factors. No statistically significa nt difference in the distribution of the polymorphism was observed between the intestinal type and diffuse type of gastric cancer in either the JBs or the NJBs. The ethnic difference in hOGG1 Ser326Cys polymorphism was much g reater than the case-control difference, and this polymorphism is unlikely to be associated with gastric cancer. (C) 2001 Elsevier Science Ireland Ltd . All rights reserved.