PURPOSE: The aim of the study is to estimate the differences in the impact of diet and physical exercise on lung cancer risk in female nonsmokers vs. smokers, and reveal effect modifications (interactions), if any.
METHODS: In a hospital based case-control study data collected by in-person interviews from 533 female lung cancer cases and 1971 controls were analyzed using unconditional logistic regression stratifying by appropriate factors. Comparison of relative risks between smokers and nonsmokers was based on confidence intervals for the ratio of relative risks.
RESULTS: Protective effects were observed for intake of milk/dairy products (OR=0.57, 95%CI 0.35-0.94), vegetables (OR=0.60, 95%CI 0.40-0.91), apples (OR=0.69), wine (OR=0.77), and physical exercise (OR=0.59, 95%CI 0.42-0.83) among smokers only, while no similar effects were found among nonsmokers. In contrast, the intake of black tea was associated with a protective effect (OR=0.66, 95%CI 0.47-0.94) among nonsmokers only.Comparing the effects of dietary items and physical activity on lung cancer risk among nonsmokers versus smokers, statistically significant effect modifications were found for black tea (P 0.005), and milk/dairy products (P 0.047). Border line effect modifications emerged for physical exercise (P 0.077).
CONCLUSION: These results indicate protective effects of some components of a healthful diet and physical exercise among smokers, and of the intake of black tea among nonsmokers.
CLINICAL IMPLICATIONS: The observed effect modifications of the impact of black tea, milk/dairy products and physical activity upon lung cancer risk in women at different levels of the smoking habit, possibly explicable by interaction, deserve further studies.
DISCLOSURE: Norbert Pauk, No Financial Disclosure Information; No Product/Research Disclosure Information