Processed meat consumption, dietary nitrosamines and stomach cancer risk in a cohort of Swedish women

Processed meat consumption has been associated with an increased risk of stomach cancer in some epidemiological studies (mainly case-control). Nitrosamines may be responsible for this association, but few studies have directly examined nitrosamine intake in relation to stomach cancer risk. We prospectively investigated the associations between intakes of processed meat, other meats and N-nitrosodimethylamine (the most frequently occurring nitrosamine in foods) with risk of stomach cancer among 61,433 women who were enrolled in the population-based Swedish Mammography Cohort. Information on diet was collected at baseline (between 1987 and 1990) and updated in 1997. During 18 years of follow-up, 156 incident cases of stomach cancer were ascertained. High consumption of processed meat, but not of other meats (i.e., red meat, fish and poultry), was associated with a statistically significant increased risk of stomach cancer. After adjustment for potential confounders, the hazard ratios for the highest compared with the lowest category of intake were 1.66 (95% CI = 1.13-2.45) for all processed meats, 1.55 (95% CI = 1.00-2.41) for bacon or side pork, 1.50 (95% CI = 0.93-2.41) for sausage or hotdogs and 1.48 (95% CI= 0.99-2.22) for ham or salami. Stomach cancer risk was 2-fold higher among women in the top quintile of N-nitrosodimethylamine intake when compared with those in the bottom quintile (hazard ratio = 1.96; 95% CI = 1.08-3.58). Our findings suggest that high consumption of processed meat may increase the risk of stomach cancer. Dietary nitrosamines might be responsible for the positive association.