Dietary factors and gastric cancer risk. A case-control study in Spain.

BACKGROUND: Evidence supports that gastric cancer has an environmental etiology, of which diet appears to be the most important component. The authors examined the effect of diet on the risk of gastric cancer.
METHODS: A case-control study of dietary factors and gastric cancer was conducted between September 1986 and March 1989 in the Barcelona metropolitan area, Spain. One hundred seventeen cases with histologically confirmed diagnosis of gastric adenocarcinoma were matched by age, gender, and whether they possessed a telephone to 234 community controls. One hundred eighty-eight (80.3%) controls were selected by random-digit telephone dialing and 46 (19.7%) by neighborhood of residence. Information about frequency and amount of consumption of 89 food items in one year was gathered by using a questionnaire, and cases and controls were interviewed in their homes by trained interviewers. Unconditional logistic regression was used for the analysis.
RESULTS: Gastric cancer risk rose with increasing intake of smoked and pickled foods (OR 3.67 for upper tertile) and salt (OR 2.11 for upper quartile). Intake of citrus fruits (OR 0.47 for upper tertile) and raw-green vegetables (OR 0.56 for upper quartile) appeared to be protective. Gastric cancer risk was not associated with intake of cereals, rice, total vegetables, and fruits as a whole.
CONCLUSIONS: These data suggest that high intake of salt and smoked and pickled food may be associated with a high risk of gastric cancer, and this association could be due to intragastric formation of nitrosamines. The negative association with citric and green vegetables consumption to be associated with the inhibition of nitrosation process.