Risk factors for stomach cancer in Brazil (II): a case-control study among Japanese Brazilians in Sao Paulo

Background: Although stomach cancer is the most frequent cancer among Japanese Brazilians, the risk factor of this cancer has not been investigated among them. Methods: A case-control study was conducted among Japanese residents in the city of Sao Paulo. Ninety-six consecutive cases of histologically confirmed stomach cancer were matched to 192 controls admitted for non-neoplastic diseases or healthy volunteer (n = 80) by age (+/- 5 years) and gender. The socio-demographic characteristics, personal and family medical history, lifetime history of tobacco use and dietary habits were probed using a structured questionnaire. Results: Frequent consumption of beef was associated with increased risk: odds ratio (OR) = 4.0 and 95% confidence interval (CI) = 1.9-8.4 for daily consumption, OR = 2.1 and 95% CI = 1.0-4.3 for 3-4 days/week) when compared with the category of lower consumption (<3 days/week) after adjustment for country of birth (Japan or Brazil), showing a dose-response pattern (P for trend = 0.001). These ORs became higher after further adjusted for fruit consumption: OR = 4.4, 95% CI = 2.1-9.4 and OR = 2.4 and 95% CI = 1.1-5.0, respectively. Daily consumption of fruit was associated with a reduction in risk (OR = 0.5, 95% CI = 0.3-1.0) after adjustment for country of birth and became statistically significant further adjusted for beef consumption (OR = 0.4, 95% CI = 0.2-0.9). There were no statistically significant associations with smoking or any other factors tested. Although some attenuation was observed in beef consumption, the observed associations were similar after excluding volunteer controls. Conclusions: The introduction of the habit of daily beef consumption among Japanese immigrants and their descendants may be associated with stomach cancer risk. The protective effect of fruit consumption was confirmed in this population.