Table 4

Associations between dietary folate intake and lung cancer risk stratified by selected variables in former smokers

Odds ratio (95% confidence interval)a for folate intake by quartilebTrend test
Lowest quartile (<25 percentile)25–50 percentile50–75 percentileHighest Quartile (>75 percentile)
Total (case = 470/control = 472)1.001.02 (0.71–1.47)0.67 (0.46–0.99)0.53 (0.35–0.80)<0.001
Alcohol drinker
 No (220/175)1.000.73 (0.41–1.30)0.58 (0.31–1.05)0.69 (0.36–1.30)0.161
 Yes (250/297)1.001.32 (0.81–2.12)0.80 (0.48–1.33)0.48 (0.28–0.82)0.002
Pack-years smoked
 <36 (191/242)1.001.08 (0.62–1.87)1.13 (0.64–1.99)0.89 (0.49–1.61)0.749
 ≥36 (279/230)1.001.02 (0.61–1.68)0.45 (0.26–0.78)0.34 (0.19–0.61)<0.001
Supplement folate intake
 No (205/211)1.000.74 (0.44–1.25)0.52 (0.29–0.95)0.33 (0.17–0.63)0.001
 Yes (265/261)1.001.41 (0.84–2.37)0.86 (0.51–1.46)0.78 (0.45–1.34)0.130
Family lung cancer history
 No (369/411)1.001.12 (0.76–1.67)0.89 (0.58–1.35)0.60 (0.38–0.94)0.016
 Yes (101/61)1.000.57 (0.19–1.69)0.16 (0.05–0.48)0.27 (0.09–0.85)0.006
  • a Odds ratio (95% confidence interval) obtained from logistic regression model with adjustment for age, sex, ethnicity, total energy intake, body mass index, family history of lung cancer, pack-year smoked, and alcohol consumption.

  • b Quartile cutpoints were based on residual energy-adjusted intake among controls.