Table 3.

RRs and 95% CIs of invasive breast cancer according to quintiles of plasma homocysteine and cysteine as well as of dietary methionine and cystine intakes in the Women's Health Study

QuintilePtrend
1 (Lowest)2345 (Highest)
Plasma levels
    Homocysteine (nmol/mL)<6.796.79–<7.957.95–<9.139.13–<11≥11
    n cases/controls182/164134/161130/163184/162182/162
    Simple RR*1.000.75 (0.54–1.05)0.72 (0.51–1.01)1.01 (0.73–1.40)1.02 (0.73–1.43)0.33
    Multivariate RR1.000.61 (0.47–0.97)0.63 (0.44–0.90)1.00 (0.70–1.42)0.92 (0.64–1.32)0.61
Cysteine (nmol/mL)<185.2185.2–<198198–<209209–<219.7≥219.7
    n cases/controls138/163150/162196/163172/162156/162
    Simple RR*1.001.23 (0.87–1.74)1.73 (1.18–2.54)1.55 (1.05–2.30)1.41 (0.93–2.13)0.11
    Multivariate RR1.001.29 (0.89–1.88)1.93 (1.27–2.94)1.67 (1.08–2.57)1.65 (1.04–2.61)0.04
Dietary intake
    Methionine (g/d)<1.611.61–<1.821.82–<2.02.0–<2.23≥2.23
    n cases/controls163/158177/160145/160159/159150/153
    Simple RR*1.001.05 (0.76–1.44)0.83 (0.60–1.14)0.95 (0.69–1.32)0.96 (0.69–1.33)0.62
    Multivariate RR1.001.06 (0.75–1.49)0.82 (0.58_1.17)0.98 (0.69–1.40)0.93 (0.65–1.32)0.55
Cystine (g/d)<0.910.91–11–<1.081.08–<1.16≥1.16
    n cases/controls185/161156/172173/157126/143154/157
    Simple RR*1.000.76 (0.56–1.04)0.94 (.69–1.28)0.76 (0.54–1.06)0.86 (0.63–1.18)0.43
    Multivariate RR1.000.82 (0.59–1.15)0.95 (0.68–1.31)0.81 (0.56–1.16)0.82 (0.58–1.15)0.29
  • *Simple models were adjusted for matching variables and age (in year) and randomized treatment assignment to aspirin and vitamin E (aspirin versus placebo, vitamin E versus placebo).

  • Multivariate models were adjusted for matching variables denoted in the legend and additionally for BMI [weight (kg)/height (m)2: <25, 25–<30, ≥30 kg/m2], physical activity (energy expenditure in kcal/wk, in quartiles), family history of breast cancer in a first-degree relative (yes, no), history of benign breast disease (yes, no), age at menarche (≤11, 12, 13, ≥14 years), parity (0, 1–2, 3–4, ≥5 children), age at first birth (≤19, 20–24, 25–29, ≥30 years), smoking status (never, past, current), alcohol consumption (never, 0.1–<5, 5–<15, ≥15 g/d), and age at menopause (<45, 45–<50, 50–<52, ≥52 years).