Table 5.
Betas (β) and standard errors (SE) for the association between factors and breast density in all women and in subgroupsa
| Characteristic | All women n = 144,018 | Women without breast cancer n = 136,283 |
|---|---|---|
| β (SE) | β (SE) | |
| Intercept | 4.82 (0.17) | 4.88 (0.17) |
| Age | −0.04 (0.001) | −0.04 (0.001) |
| Current BMI | −0.12 (0.003) | −0.12 (0.003) |
| Family history of breast cancer | 0.09 (0.02) | 0.09 (0.02) |
| BMI <30 | −0.53 (0.11) | −0.53 (0.11) |
| Postmenopausal | −0.43 (0.09) | −0.43 (0.09) |
| HT use | −1.22 (0.11) | −1.25 (0.11) |
| Age at menarche | ||
| 15+ | −0.01 (0.10) | −0.03 (0.11) |
| 14 | 0.04 (0.10) | 0.01 (0.10) |
| 13 | −0.01 (0.08) | −0.03 (0.08) |
| 12 | 0.08 (0.08) | 0.06 (0.08) |
| 11 | 0.04 (0.08) | 0.02 (0.08) |
| BMI <30 * Age at menarche | ||
| 15+ | 0.30 (0.12) | 0.32 (0.12) |
| 14 | 0.24 (0.11) | 0.28 (0.11) |
| 13 | 0.22 (0.09) | 0.24 (0.10) |
| 12 | 0.12 (0.09) | 0.15 (0.10) |
| 11 | 0.11 (0.10) | 0.14 (0.10) |
| Age at first birth | ||
| Nulliparous | 0.38 (0.16) | 0.13 (0.17) |
| 35+ | 0.19 (0.22) | 0.25 (0.23) |
| 30–34 | −0.19 (0.15) | −0.18 (0.15) |
| 25–29 | −0.11 (0.12) | −0.12 (0.12) |
| 20–24 | 0.14 (0.11) | 0.13 (0.11) |
| BMI <30 * Age at first birth | ||
| Nulliparous | 0.57 (0.10) | 0.59 (0.11) |
| 35+ | 0.41 (0.18) | 0.40 (0.18) |
| 30–34 | 0.31 (0.11) | 0.32 (0.12) |
| 25–29 | 0.12 (0.08) | 0.15 (0.08) |
| 20–24 | 0.06 (0.06) | 0.06 (0.06) |
| Postmenopausal * Age at first birth | ||
| Nulliparous | 0.09 (0.15) | 0.10 (0.15) |
| 35+ | −0.08 (0.19) | −0.14 (0.19) |
| 30–34 | 0.27 (0.13) | 0.26 (0.13) |
| 25–29 | 0.25 (0.11) | 0.23 (0.11) |
| 20–24 | −0.05 (0.10) | −0.04 (0.11) |
| Paritya | ||
| 1 | 0.29 (0.09) | 0.28 (0.09) |
| 2 | 0.22 (0.07) | 0.23 (0.07) |
| 3 | 0.14 (0.07) | 0.17 (0.07) |
| 4 | 0.09 (0.07) | 0.11 (0.08) |
| BMI <30 * Parityb | ||
| 1 | 0.30 (0.10) | 0.30 (0.10) |
| 2 | 0.22 (0.07) | 0.20 (0.08) |
| 3 | 0.18 (0.08) | 0.15 (0.08) |
| 4 | 0.09 (0.08) | 0.07 (0.09) |
| Age * HT use | 0.03 (0.002) | 0.03 (0.002) |
aBased on a multivariable model containing all terms shown in the table
bThe nulliparous parameter and its interaction with BMI were set to 0, since these variables were linear combinations of other variables