Isoflavone intake and risk of lung cancer: a prospective cohort study in Japan

Am J Clin Nutr. 2010 Mar;91(3):722-8. doi: 10.3945/ajcn.2009.28161. Epub 2010 Jan 13.

Abstract

Background: Although case-control studies support the idea that soy foods or isoflavone intake is associated with a decreased risk of lung cancer, little evidence is available from prospective cohort studies. Moreover, no prospective study has addressed this association in men.

Objective: We investigated the association between isoflavone intake and lung cancer incidence.

Design: We conducted a population-based prospective cohort study in 36,177 men and 40,484 women aged 45-74 y with no history of cancer at baseline in 1995-1999. Participants responded to a validated questionnaire, which included 138 food items. We used Cox proportional hazards regression analysis to estimate the hazard ratios (HRs) and 95% CIs of lung cancer incidence according to isoflavone intake, which was estimated by genistein content from soy foods.

Results: During 11 y (671,864 person-years) of follow-up, we documented 481 male and 178 female lung cancer cases. In men we found an inverse association between isoflavone intake and risk of lung cancer in never smokers (n = 13,051; multivariate HR in the highest compared with the lowest quartile of isoflavone intake: 0.43; 95% CI: 0.21, 0.90; P for trend = 0.024) but not in current or past smokers. A similar, nonsignificant inverse association was seen in never-smoking women (n = 38,211; HR: 0.67; 95% CI: 0.41, 1.10; P for trend = 0.135). We also tested effect modification by smoking status (P for interaction = 0.085 in men and 0.055 in men and women combined).

Conclusion: In a large-scale, population-based, prospective study in Japan, isoflavone intake was associated with a decreased risk of lung cancer in never smokers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Carcinoma / prevention & control*
  • Diet Surveys
  • Female
  • Food Analysis
  • Genistein / analysis
  • Humans
  • Isoflavones / therapeutic use*
  • Japan
  • Lung Neoplasms / prevention & control*
  • Male
  • Middle Aged
  • Phytoestrogens / therapeutic use*
  • Plant Extracts / therapeutic use*
  • Proportional Hazards Models
  • Prospective Studies
  • Risk Factors
  • Sex Factors
  • Smoking*
  • Soy Foods*
  • Soybeans / chemistry
  • Surveys and Questionnaires

Substances

  • Isoflavones
  • Phytoestrogens
  • Plant Extracts
  • Genistein