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) | |||||
|---|---|---|---|---|---|
| ≤1.52 | 1.53–2.77 | >2.77 | |||
| Body mass index (by median)b | |||||
| ≤23.95 | 1.0 (reference) | 3.5 (1.1–11.0) | 3.8 (1.2–12.0) | ||
| >23.95 | 1.1 (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 years | 1.0 (reference) | 1.9 (0.7–4.8) | 3.1 (1.1–8.6) | ||
| <15 years | 1.0 (0.3–3.2) | 1.6 (0.6–4.6) | 6.6 (2.2–20.3) | ||
| P for interaction, 0.32 | |||||
| Age at menopausec | |||||
| <50 | 1.0 (reference) | 1.6 (0.4–6.2) | 3.7 (0.9–14.4) | ||
| ≥50 | 1.5 (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.