Purpose: The purpose of this study is to investigate the association of cigarette smoking with gastric cancer.
Methods: 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.
Results: 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.
Conclusions: 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.