Table III.
Odds ratios from logistic regressions for ER/P53 subtypes.
| Tumor characteristics1 | |||||
|---|---|---|---|---|---|
| ER+ | ER− | ||||
| Risk factor2 | P53+ n = 205 |
P53− n = 776 |
P53+ n = 323 |
P53− n = 448 |
Test for heterogeneity |
| Age at diagnosis (×10 years) | 2.1 (1.4–3.2) | 1.9 (1.6–2.4) | 0.8 (0.7–1.0) | 1.2 (1.0–1.5) | < 0.001 |
| Age at menarche (×2 years) | 1.0 (0.8–1.2) | 0.9 (0.8–1.0) | 1.0 (0.9–1.2) | 1.0 (0.9–1.2) | 0.04 |
| Nulliparous | 1.9 (1.3–2.6) | 1.4 (1.1–1.7) | 0.7 (0.5–1.0) | 1.2 (0.9–1.5) | 0.001 |
| Age at 1st Birth (×5 years) | 1.2 (1.0–1.4) | 0.9 (0.8–1.0) | 1.1 (0.9–1.2) | 1.1 (1.0–1.2) | 0.67 |
| Breastfeeding (×6 months) | 1.0 (0.9–1.1) | 0.9 (0.9–1.0) | 0.8 (0.7–0.9) | 0.9 (0.9–1.0) | 0.12 |
| Postmenopausal | 0.4 (0.3–0.6) | 0.6 (0.4–0.7) | 0.9 (0.6–1.3) | 0.6 (0.4–0.8) | 0.01 |
| BMI (premenopausal ×20 units) | 1.1 (0.5–2.3) | 0.7 (0.4–1.0) | 1.2 (0.7–2.2) | 1.9 (1.2–3.0) | 0.01 |
| BMI (postmenopausal ×20 units) | 0.9 (0.4–2.0) | 0.8 (0.5–1.3) | 1.0 (0.5–1.9) | 0.8 (0.4–1.4) | 0.96 |
| Ever use of OCs | 1.0 (0.7–1.4) | 0.9 (0.8–1.1) | 1.0 (0.8–1.3) | 1.1 (0.8–1.3) | 0.82 |
| Family history of BC | 2.2 (1.5–3.3) | 2.1 (1.7–2.7) | 2.0 (1.4–2.8) | 1.6 (1.2–2.2) | 0.44 |
In all four columns, the entries are the relative risks, versus controls, of tumors characterized by the combination of markers: (ER+,P53+), (ER+,P53−), (ER−,P53−) and (ER−,P53−), respectively.
All analyses are adjusted for study center in addition to the factors in the table. For variables involving structural exclusions such as age at first birth for women with no children, we assigned the mean age at first birth among parous women (22.8) to the women with no children. Similarly, we assigned 5.3 months of breast feeding to nulliparous women, a postmenopausal BMI of 23.9 for premenopausal women and a premenopausal BMI of 24.8 for postmenopausal women. We recommend this strategy for structural exclusions of this nature [23]. It ensures that the influence of these structurally excluded subjects is minimized with respect to the estimation of the odds ratios for these factors.