The association of cigarette smoking with gastric cancer: the multiethnic cohort study

The purpose of this study is to investigate the association of cigarette smoking with gastric cancer. Over 215,000 men and women, representing five ethnic groups (African Americans, Japanese Americans, Latino Americans, Native Hawaiians, and Whites), completed a mailed questionnaire, 1993-1996. After an average follow-up of 7.3 years, 454 men and 242 women were diagnosed with gastric adenocarcinoma. Cox proportional hazard models were used to calculate multivariate-adjusted hazard ratios and 95% confidence intervals. Current cigarette smokers had elevated hazard ratios compared with never smokers among men (HR = 1.98; 95% CI 1.46-2.70) and women (HR = 1.78; 95% CI 1.23-2.57). This positive association was consistent across all five ethnicities. Former smokers had an elevated risk among men, but not among women. There was a significant trend by intensity (cigarettes per day) and duration (years) of smoking among all current smokers. After separation by anatomic location of their tumor, ever smokers had a higher risk for gastric cardia cancer (HR = 2.86; 95% CI 1.66-4.93) than for distal gastric cancer (HR = 1.52; 95% CI 1.25-1.86) among men and women combined. Analysis by histologic tumor type showed a stronger association between current smoking and the intestinal type. Overall, this study shows an association of current cigarette smoking with gastric cancer in both sexes, consistency of this effect across five ethnic groups, evidence for a dose-response effect of smoking in both sexes, a stronger effect for cardia than for distal gastric cancer, and a stronger association for intestinal than for diffuse gastric cancer.