Background: Diet rich in isothiocyanates, found in cruciferous vegetables such as broccoli, cabbage, cauliflower, Brussels sprouts, and turnips, or quercetin, found in apples, grapes, onions, and broccoli, may modulate the risk of lung cancer via regulation of tobacco-related carcinogen metabolism, cell cycle arrest, apoptosis, and anti-inflammatory activities. Objective: To investigate the association between lung cancer risk and dietary intakes rich in isothiocyanates and quercetin in the Environment And Genetics in Lung cancer Etiology (EAGLE), a population-based case-control study of lung cancer in Italy. Methods: Between 2002 and 2005, 2101 primary lung cases were enrolled from 13 hospitals within the Lombardy Region of Italy. Healthy controls (2120) were randomly selected and recruited from the same residential area as lung cancer cases. Cases and controls were matched on gender, city of residence, and age (±5 years). Comprehensive epidemiological data were collected through an interview-based computer-assisted questionnaire and dietary intakes via a brief self-administered questionnaire. Logistic regression analysis was used to compute odds ratios (ORs) and 95% confidence intervals (CIs). All analyses were adjusted for matching variables, body mass index, education, alcohol consumption, and smoking history (cigarette intensity, duration of cigarette smoking, and years since last cigarette smoked for former smokers). Results: For comparisons of the highest-versus-lowest quintile of intake frequency, statistically significant protective associations for lung cancer were observed for quercetin-rich foods (OR: 0.65; 95% CI: 0.51-0.82; p-trend: 0.001), total fruits (OR: 0.74; 95% CI: 0.58-0.95; p-trend: 0.02), and total intake of fruits and vegetables (OR: 0.76; 95% CI: 0.59-0.97; p-trend: 0.02). The protective association was more pronounced among heavy ever-smokers whose diet was high in quercetin-rich foods (> 36 pack-years, OR: 0.45; 95% CI: 0.3-0.65; p-trend: 0.001). No associations were observed for intakes of isothiocyanate-rich foods (OR: 1.1; 95% CI: 0.85-1.44; p-trend: 0.68) or total vegetables (OR: 0.92; 95% CI: 0.72-1.17; p-trend: 0.44). Conclusion: Our data suggest that a diet rich in fruits and vegetables, and particularly those rich in quercetin may reduce the risk of lung cancer, especially in smokers. If confirmed in prospective studies, these results may contribute to the development of preventive strategies against lung cancer that are complementary to smoking cessation programs.
99th AACR Annual Meeting-- Apr 12-16, 2008; San Diego, CA