Table 2.

HRs and 95% CIs of breast cancer by quartiles of steroid hormone levels

Quartiles*Doubling hormone concentrationPtrend
Q1Q2Q3Q4
Total estradiol
    Cases/PY§39/1,95047/1,94649/1,91760/1,904
    HR (95% CI)Reference1.09 (0.66-1.79)1.21 (0.74-1.99)1.44 (0.89-2.35)1.45 (0.91-2.30)0.12
Free estradiol
    Cases/PY§37/1,93439/1,94853/1,90466/1,923
    HR (95% CI)Reference1.05 (0.62-1.77)1.49 (0.90-2.44)1.75 (1.06-2.89)1.61 (1.12-2.33)0.01
Estrone sulfate
    Cases/PY§35/1,95448/1,91443/1,93966/1,898
    HR (95% CI)Reference1.53 (0.93-2.52)1.20 (0.71-2.03)2.05 (1.24-3.37)1.52 (1.11-2.07)<0.01
Testosterone
    Cases/PY§45/2,00747/1,93448/1,93056/1,946
    HR (95% CI)Reference1.09 (0.68-1.74)1.10 (0.68-1.78)1.25 (0.78-2.01)1.11 (0.88-1.40)0.37
DHEAS
    Cases/PY§45/1,98447/1,94044/1,95761/1,948
    HR (95% CI)Reference1.06 (0.65-1.74)1.06 (0.64-1.73)1.41 (0.88-2.27)1.15 (0.94-1.42)0.17
Androstenedione
    Cases/PY§36/1,95849/1,94456/1,95055/1,970
    HR (95% CI)Reference1.39 (0.85-2.28)1.66 (1.03-2.69)1.49 (0.91-2.44)1.24 (0.97-1.57)0.08
SHBG
    Cases/PY§79/1,98551/1,96036/1,94031/1,955
    HR (95% CI)Reference0.57 (0.37-0.88)0.38 (0.24-0.61)0.33 (0.19-0.55)0.41 (0.29-0.60)<0.01

NOTE: HRs from the Cox model were adjusted for country of birth, age at menarche, parity and age at first pregnancy, duration of lactation, oral contraceptive use, HRT use, alcohol consumption, energy from diet, smoking, BMI, level of education, and level of physical activity. Estimates were based on the following number of women (cases): total estradiol, 1,019 (195); free estradiol, 1,018 (195); estrone sulfate, 1,014 (192); testosterone, 1,031 (196); DHEAS, 1,032 (197); androstenedione, 1,031 (196); SHBG, 1,034 (197).

  • *Quartiles were adjusted for variations between batches and by age at time of blood collection, according to the procedure described in the method section.

  • Estimates from the model including the pseudocontinuous variable log2 transformed.

  • Test for linear trend using the pseudocontinuous variable log2 transformed.

  • §Breast cancer cases and person-years (PY).