Table 5.
Waist-hip ratio and breast cancer risk by body mass index in Nigerian women, 1998–2009
| WHR | Cases | Controls | Age-adjusted OR (95% CI) | Adjusted OR (95% CI)† |
|---|---|---|---|---|
| BMI < 25kg/m2 | ||||
| < 0.77 | 132 | 205 | 1.0 (ref.) | 1.0 (ref.) |
| 0.77 to <0.81 | 112 | 168 | 0.86 (0.61–1.21) | 0.85 (0.58–1.24) |
| 0.81 to <0.87 | 196 | 148 | 1.71 (1.23–2.36) | 1.86 (1.31–2.65) |
| ≥ 0.87 | 165 | 82 | 2.52 (1.75–3.61) | 2.81 (1.90–4.16) |
| P for trend | <0.001 | <0.001 | ||
| Mean ± SD | 0.832±0.093 | 0.799±0.069 | ||
| Per 0.1 unit | 1.60 (1.35–1.89) | 1.72 (1.43–2.07) | ||
|
| ||||
| BMI ≥ 25kg/m2 | ||||
| < 0.77 | 76 | 93 | 1.0 (ref.) | 1.0 (ref.) |
| 0.77 to <0.81 | 87 | 98 | 1.14 (0.74–1.75) | 1.23 (0.76–1.99) |
| 0.81 to <0.87 | 195 | 194 | 1.44 (0.98–2.10) | 1.63 (1.06–2.50) |
| ≥ 0.87 | 219 | 148 | 1.64 (1.12–2.40) | 1.70 (1.11–2.61) |
| P for trend | 0.005 | 0.01 | ||
| Mean ± SD | 0.850±0.079 | 0.836±0.075 | ||
| Per 0.1 unit | 1.23 (1.04–1.44) | 1.21 (1.01–1.45) | ||
|
| ||||
| P for interaction* | 0.031 | 0.016 | ||
Abbreviations: BMI, body mass index; WHR, waist-hip ratio; OR, odds ratio; CI, confidence interval; SD, standard deviation
*
Interaction between waist to hip ratio and body mass index
†
Adjusted for age at diagnosis or interview (categorical), ethnicity, education (categorical), age at menarche (continuous), number of live birth (categorical), age at first live birth (continuous), duration of breastfeeding (categorical), menopausal status, family history of breast cancer, benign breast disease, hormonal contraceptive use, alcohol drinking, and height (continuous).
Categories of waist-hip ratio are based on quartiles in controls.