Heme iron from meat and risk of adenocarcinoma of the esophagus and stomach.

Iron can cause oxidative stress and DNA damage, and heme iron can catalyze endogenous formation of N-nitroso compounds, which are potent carcinogens. Dietary iron promotes esophageal cancer incidence in animal studies and has been identified as a growth factor for Helicobacter pylori, an established risk factor for stomach cancer. We conducted a population-based case-control study of adenocarcinoma of the esophagus (n=124) and stomach (n=154) and 449 controls in Nebraska. Heme iron and total iron intake were estimated from a food frequency questionnaire and databases of heme and total iron. We used logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for known risk factors. Esophageal cancer was positively associated with higher intakes of heme iron (ORQ4 vs. Q1=3.04, 95% CI: 1.20-7.72; P trend=0.009) and total iron from meat sources (ORQ4 vs. Q1=2.67, 95% CI: 0.99-7.16; P trend=0.050). Risk of stomach cancer was elevated among those with higher intakes of heme iron (ORQ4 vs.Q1=1.99, 95% CI: 1.00-3.95; P trend=0.17) and total iron from meat (OR=2.26, 95% CI: 1.14-4.46; P trend=0.11). Iron intake from all dietary sources was not significantly associated with risk of either cancer. Our results suggest that high intakes of heme and iron from meat may be important dietary risk factors for esophageal and stomach cancer and may partly explain associations with red meat.