Table 4

Interaction of the urinary ratio of 6β-OHC:cortisol with body mass index and menstrual factors on the risk of breast cancer, Shanghai Breast Cancer Study, 1996–98

ORa (95% CI) by cortisol ratios (by tertile)
≤1.521.53–2.77>2.77
Body mass index (by median)b
 ≤23.951.0 (reference)3.5 (1.1–11.0)3.8 (1.2–12.0)
 >23.951.1 (0.4–3.3)1.5 (0.5–4.4)8.3 (2.4–28.4)
P for interaction, 0.046
Age at menarcheb
 ≥15 years1.0 (reference)1.9 (0.7–4.8)3.1 (1.1–8.6)
 <15 years1.0 (0.3–3.2)1.6 (0.6–4.6)6.6 (2.2–20.3)
P for interaction, 0.32
Age at menopausec
 <501.0 (reference)1.6 (0.4–6.2)3.7 (0.9–14.4)
 ≥501.5 (0.4–5.2)2.4 (0.6–9.3)6.0 (1.4–25.5)
P for interaction, 0.99
  • a Adjusted for education level, waist-to-hip ratio, age at first live birth, and two of the following three variables that were not evaluated as the stratified variable: body mass index, age at menarche, and age at menopause.

  • b Analyses were restricted to 144 pairs of cases and controls who were over 45 years of age.

  • c Based on 92 pairs of cases and controls who had natural menopause and were over 45 years of age.