A nested case-control study of cruciferous vegetables intake, urinary isothiocyanates level and lung cancer risk among men in urban Shanghai

Abstract

Objective: To investigate the association between consumption of cruciferous vegetables (CV), level of urinary isothiocyanates (ITC) and the risk of lung cancer among man in urban Shanghai. Methods: A nested case-control study was conducted within the Shanghai Men's Health Study. Using incidence density sampling with a 2∶1 control to case selection ratio, 885 controls were selected to match 443 lung cancer cases diagnosed prior December 31, 2010. A food-frequency questionnaire was administered to estimate CV consumption. The high performance liquid chromatography method was applied to measure urinary ITC level. The CV intake and urinary ITC level were divided into quartiles according to distribution of control group. The lowest quartile was as a reference group. Conditional logistic regression model was used to analyze the relationship between CV intake, urinary ITC level and the risk of lung cancer. Results: The cruciferous vegetables intake median (P(25), P(75)) in cases and controls were 80.05 (46.89, 129.04) and 97.68 (55.25, 151.72) g/d (Z=-3.93, P<0.001). The urinary ITC level were 1.256 (0.474, 3.836) and 1.244 (0.484, 3.004) μmol/g Cr (Z=-0.39, P=0.697). After adjusting for potential confounding factors such as age, education level, smoking and alcohol consumption, for urinary ITC level, the OR(95%CI) for the highest quartile(≥3.004 μmol/g Cr) was 1.25 (0.87-1.80) compared with the lowest quartile(<0.484 μmol/g). For CV intake, the OR(95%CI) for the highest quartile(≥151.71 g/d) was 0.66 (0.43-1.02) compared with the lowest quartile(<55.25 g/d). Conclusion: No association was found between the CV intake, urinary ITC level and lung cancer risk in men.