Vitamin K intake and risk of lung cancer: the Japan Collaborative Cohort Study.

Abstract

Limited reports from human prospective studies investigated the possible role of vitamin K in the development of lung cancer although vitamin K's anticarcinogenic activities were verified from several in vitro and in vivo studies. We investigated the associations between total vitamin K intake from food and the development of lung cancer based on this large prospective cohort study. A validated food frequency questionnaire was used to examine vitamin K intake among 42,166 (16,341 men and 25,825 women) at the Japan Collaborative Cohort Study's baseline (1988-1990). Hazard ratios (HRs) and 95% confidence intervals (CIs) of incident lung cancer were calculated using the Cox proportional hazard regression method based on vitamin K consumption quartiles. 430 cases (308 males and 122 women) of lung cancer were documented during a total of 564,127 person-years of follow-up (median follow-up= 14.6 years). Vitamin K consumption was shown to be inversely related to lung cancer risk; the multivariable HR (95 % CI) for the highest vs. lowest quartiles was 0.67 (0.46-0.96; p for trend = 0.010). This relationship appears to be stronger in males [0.62 (0.40-0.96); p for trend=0.016] than in females [0.82 (0.42-1.61); p for trend=0.39] (p for interaction=0.012), and in ever smokers [0.57 (0.36-0.91); p for trend=0.006] than in never smokers [0.79 (0.40-1.55); p for trend=0.37] (p for interaction= 0.30). The individuals' age, BMI, or alcohol consumption status had no effect on the observed connection. Vitamin K consumption reduces the risk of lung cancer. More research is needed to clarify the molecular processes behind this connection.