Table 3.
BMI at age 18, current BMI and risk of breast cancer by menopausal status
| Cases/total n | Age-adjusted HR (95% CI) | P-value | Cases/total n | Multivariable HR (95% CI)a | P-value | |
|---|---|---|---|---|---|---|
| BMI at age 18, kg/m2 | ||||||
| Pre-menopausal | ||||||
| <18.8 | 42/522 | 1.06 (0.69, 1.61) | 0.80 | 42/522 | 1.06 (0.69, 1.61) | 0.80 |
| 18.8 to <20.3 | 45/522 | 1.00 (Ref) | Ref | 45/522 | 1.00 (Ref) | Ref |
| 20.3 to <22.1 | 47/486 | 1.26 (0.84, 1.90) | 0.27 | 47/486 | 1.26 (0.84, 1.90) | 0.27 |
| ≥22.1 | 42/506 | 1.14 (0.75, 1.74) | 0.53 | 42/506 | 1.14 (0.75, 1.73) | 0.56 |
| P-trend | 0.65 | 0.68 | ||||
| Post-menopausal | ||||||
| <18.8 | 25/289 | 0.66 (0.41, 1.08) | 0.10 | 25/289 | 0.66 (0.41, 1.07) | 0.09 |
| 18.8 to <20.3 | 47/376 | 1.00 (Ref) | Ref | 47/376 | 1.00 (Ref) | Ref |
| 20.3 to <22.1 | 33/330 | 0.71 (0.46, 1.11) | 0.13 | 33/330 | 0.73 (0.47, 1.14) | 0.16 |
| ≥22.1 | 22/349 | 0.49 (0.30, 0.82) | 0.006 | 22/349 | 0.49 (0.30, 0.82) | 0.006 |
| P-trend | 0.33 | 0.34 | ||||
| Current BMI, kg/m2 | ||||||
| Pre-menopausal | ||||||
| <20.9 | 35/578 | 0.74 (0.47, 1.14) | 0.17 | 35/578 | 0.74 (0.48, 1.15) | 0.18 |
| 20.9 to <23.3 | 47/566 | 1.00 (Ref) | Ref | 47/566 | 1.00 (Ref) | Ref |
| 23.3 to <26.6 | 56/517 | 1.37 (0.93, 2.02) | 0.11 | 56/517 | 1.34 (0.91, 1.98) | 0.14 |
| ≥26.6 | 39/462 | 1.00 (0.65, 1.53) | 0.99 | 39/462 | 0.97 (0.63, 1.48) | 0.88 |
| P-trend | 0.22 | 0.31 | ||||
| Post-menopausal | ||||||
| <20.9 | 16/183 | 0.88 (0.48, 1.58) | 0.66 | 16/183 | 0.87 (0.48, 1.57) | 0.65 |
| 20.9 to <23.3 | 35/312 | 1.00 (Ref) | Ref | 35/312 | 1.00 (Ref) | Ref |
| 23.3 to <26.6 | 40/409 | 0.78 (0.50, 1.23) | 0.29 | 40/409 | 0.78 (0.49, 1.22) | 0.27 |
| ≥26.6 | 45/547 | 0.68 (0.43, 1.05) | 0.08 | 45/547 | 0.66 (0.42, 1.03) | 0.07 |
| P-trend | 0.34 | 0.27 |
a
The multivariable model adjusted for age at baseline (continuous), BRCA mutation type (BRCA1 or BRCA2), country of residence (North America, Poland or other) and parity (ever or never had a live birth; time-dependent).