Smoking and alcohol drinking in relation to risk of gastric cancer: A population‐based, prospective cohort study

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Abstract
The relations between tobacco, alcohol and risk of gastric cancer need to be established, and any gain from preventive measures should be estimated. We conducted a population‐based, prospective cohort study in Nord‐Trondelag county in Norway. During 1984–1986, adult residents were invited to a health survey and they answered questionnaires that assessed exposure to tobacco and alcohol, together with potential confounding factors. The exposure assessment regarding alcohol was limited to a 14‐day period. New gastric cancers that occurred during follow‐up (1984–2002) were identified by linkage to the Norwegian Cancer Registry. Cox proportion hazards regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CI), adjusted for sex, education and body mass index. Follow‐up of 1,117,648 person‐years at risk among 69,962 cohort members revealed 251 gastric cancers, including 224 noncardia cancers. The risk was almost twice as high in daily smokers (HR = 1.88 [CI 95% = 1.33–2.67]) as in never smokers. Independent dose‐response relations were found with earlier age at initiation (p = 0.02), frequency (p = 0.00) and duration of smoking (p = 0.00). Attributable risk (AR) of gastric cancer among current smokers was 8.7/100,000 person‐years and the corresponding population AR was 18.4%. No statistically significant associations between various degrees of exposure to alcohol and risk of gastric cancer was revealed, but combined high use of cigarettes (>20/day) and alcohol (>5 occasions/14 days) increased the risk of noncardia gastric cancer nearly 5‐fold (HR = 4.90 [95% CI = 1.90–12.62]), compared to nonusers. It is concluded that smoking is a dose‐dependent risk factor for gastric cancer. Combined high exposure to smoking and alcohol further increases the risk. Successful preventive measures could considerably reduce the incidence of gastric cancer.