Table 3.

Risk of lung cancer in relation to dietary soybean products and isoflavonoids (Singapore Chinese Health Study 1993-2005, women only)

Person-yearsAll lung cancers
Adenocarcinomas only
Other histologic types
No. of casesRR* (95% CI)No. of casesRR* (95% CI)No. of casesRR* (95% CI)
Tofu products and soybean drink (g/d)
    All women
        Q183,2201031.00401.00631.00
        Q285,656810.93 (0.69-1.24)391.10 (070-1.71)420.82 (0.55-1.21)
        Q386,141590.77 (0.55-1.06)280.85 (0.52-1.40)310.71 (0.46-1.10)
        Q485,504550.75 (0.53-1.05)310.99 (0.61-1.60)240.58 (0.36-0.94)
        P for trend0.0480.720.019
    Never smokers
        Q173,952631.00301.00331.00
        Q278,842490.81 (0.56-1.81)311.07 (0.65-1.77)180.58 (0.33-1.04)
        Q380,204390.69 (0.46-1.03)220.79 (0.45-1.38)170.60 (0.33-1.08)
        Q479,252380.71 (0.47-1.07)250.94 (0.55-1.63)130.49 (0.26-0.95)
        P for trend0.0600.590.028
    Ever smokers
        Q19,268401.00101.00301.00
        Q26,814321.16 (0.72-1.86)81.26 (0.49-3.23)241.15 (0.67-1.98)
        Q35,937200.94 (0.54-1.62)61.21 (0.43-3.39)140.86 (0.45-1.64)
        Q46,252170.81 (0.45-1.46)61.26 (0.44-3.59)110.68 (0.33-1.38)
        P for trend0.460.660.26
Total isoflavonoids (mg/1,000 kcal/d)
    All women
        Q182,897941.00391.00551.00
        Q285,599820.97 (0.72-1.3)381.03 (0.66-1.62)440.92 (0.62-1.38)
        Q386,223660.83 (0.6-1.14)310.90 (0.55-1.44)350.78 (0.51-1.21)
        Q485,803560.74 (0.53-1.04)300.90 (0.55-1.47)260.62 (0.38-1.00)
        P for trend0.0590.570.042
    Never smokers
        Q174,103581.00291.00291.00
        Q278,933530.90 (0.62-1.31)301.02 (0.61-1.70)230.80 (0.46-1.38)
        Q379,794460.83 (0.56-1.23)270.96 (0.56-1.63)190.71 (0.39-1.27)
        Q479,421320.59 (0.38-0.91)220.79 (0.45-1.39)100.38 (0.18-0.80)
        P for trend0.0210.410.011
    Ever smokers
        Q18,793361.00101.00261.00
        Q26,666291.12 (0.68-1.84)81.21 (0.47-3.10)211.11 (0.62-1.99)
        Q36,429200.82 (0.47-1.43)40.68 (0.21-2.20)160.87 (0.46-1.64)
        Q46,383241.10 (0.64-1.89)81.53 (0.58-4.01)160.97 (0.50-1.85)
        P for trend0.990.630.75
  • * Adjusted for age at interview, year of interview (1993-1995, 1996-1998), dialect group (Cantonese, Hokkien), educational level (none, primary, secondary, or higher), body mass index, total vegetable intake, total fruit /juice intake, β-cryptoxanthin, total isothiocyanates, and (except for nonsmokers) duration of smoking (years), cigarettes per day, and number of years since quitting.

  • Median values for quartiles of tofu products and soybean drink intake: Q1, 30.7 g/d; Q2, 66.1 g/d; Q3, 108.8 g/d; Q4, 197.7 g/d.

  • Median values for quartiles of total isoflavonoid intake (expressed as nutrient densities): Q1, 4.0 mg/1,000 kcal/d; Q2, 8.4 mg/1,000 kcal/d; Q3, 13.1 mg/1,000 kcal/d; Q4, 22.0 mg/1,000 kcal/d.