Table 4.
Adjusteda odds ratio (OR) and 95% confidence interval (CI) for joint effect of BMI at age 18 years and recent BMI in relation to risk of breast cancer overall and luminal-like subtype in premenopausal women
| BMI at age 18 years, kg/m2 | Recent BMI, kg/m2 | Controls | All cases | luminal-like (ER+ and/or PR+) | ||
|---|---|---|---|---|---|---|
| Number | Number | OR (95% CI) | Number | OR (95% CI) | ||
| Overall | ||||||
| < 20.0 | < 25.0 | 472 | 952 | Referent | 540 | Referent |
| < 20.0 | 25.0–29.9 | 96 | 184 | 0.93 (0.70–1.24) | 92 | 0.79 (0.56–1.13) |
| < 20.0 | ≥ 30.0 | 20 | 51 | 1.21 (0.69–2.13) | 24 | 0.99 (0.50–1.96) |
| 20.0–24.9 | < 25.0 | 265 | 555 | 1.03 (0.85–1.25) | 311 | 1.00 (0.79–1.26) |
| 20.0–24.9 | 25.0–29.9 | 171 | 302 | 0.87 (0.69–1.10) | 151 | 0.77 (0.58–1.02) |
| 20.0–24.9 | ≥ 30.0 | 107 | 210 | 0.86 (0.65–1.13) | 115 | 0.84 (0.60–1.17) |
| ≥ 25.0 | < 25.0 | 21 | 38 | 0.89 (0.50–1.58) | 17 | 0.65 (0.32–1.35) |
| ≥ 25.0 | 25.0–29.9 | 32 | 47 | 0.75 (0.46–1.22) | 26 | 0.79 (0.43–1.44) |
| ≥ 25.0 | ≥ 30.0 | 73 | 88 | 0.54 (0.38–0.78) | 40 | 0.46 (0.29–0.73) |
| Restricted to studies in which cases’ ER/PR/HER2 status determined in a central laboratory | ||||||
| < 20.0 | < 25.0 | 342 | 448 | Referent | 183 | Referent |
| < 20.0 | 25.0–29.9 | 70 | 86 | 0.94 (0.66–1.35) | 31 | 0.79 (0.49–1.29) |
| <20.0 | ≥ 30.0 | 16 | 21 | 1.03 (0.52–2.05) | 6 | 0.67 (0.25–1.83) |
| 20.0–24.9 | < 25.0 | 186 | 253 | 1.05 (0.83–1.34) | 103 | 1.03 (0.75–1.42) |
| 20.0–24.9 | 25.0–29.9 | 132 | 148 | 0.86 (0.65–1.15) | 55 | 0.75 (0.51–1.11) |
| 20.0–24.9 | ≥ 30.0 | 81 | 89 | 0.78 (0.55–1.11) | 37 | 0.79 (0.50–1.25) |
| ≥ 25.0 | < 25.0 | 15 | 23 | 1.09 (0.55–2.16) | 8 | 0.83 (0.33–2.08) |
| ≥ 25.0 | 25.0–29.9 | 27 | 23 | 0.68 (0.38–1.22) | 11 | 0.76 (0.36–1.62) |
| ≥ 25.0 | ≥ 30.0 | 58 | 41 | 0.52 (0.33–0.81) | 15 | 0.46 (0.25–0.86) |
| Restricted to invasive cases | ||||||
| < 20.0 | < 25.0 | 472 | 849 | Referent | 485 | Referent |
| < 20.0 | 25.0–29.9 | 96 | 169 | 0.94 (0.70–1.26) | 86 | 0.83 (0.58–1.20) |
| < 20.0 | ≥ 30.0 | 20 | 51 | 1.35 (0.77–2.38) | 24 | 1.13 (0.56–2.28) |
| 20.0–24.9 | < 25.0 | 265 | 506 | 1.04 (0.85–1.27) | 287 | 1.03 (0.81–1.32) |
| 20.0–24.9 | 25.0–29.9 | 171 | 286 | 0.92 (0.72–1.17) | 143 | 0.84 (0.62–1.13) |
| 20.0–24.9 | ≥ 30.0 | 107 | 201 | 0.89 (0.67–1.18) | 114 | 0.94 (0.67–1.34) |
| ≥ 25.0 | < 25.0 | 21 | 33 | 0.87 (0.48–1.59) | 14 | 0.58 (0.27–1.26) |
| ≥ 25.0 | 25.0–29.9 | 32 | 44 | 0.80 (0.48–1.32) | 25 | 0.89 (0.48–1.66) |
| ≥ 25.0 | ≥ 30.0 | 73 | 85 | 0.58 (0.40–0.84) | 40 | 0.53 (0.33–0.85) |
Abbreviations: ER estrogen receptor, PR progesterone receptor, HER2 human epidermal growth factor receptor-2, BMI body mass index
aORs obtained from multivariable polychotomous unconditional logistic regression models with adjustment for source study, study site, race, education, reference age, first-degree breast cancer family history, age at menarche, number of completed pregnancies, lifetime recreational physical activity, alcohol intake, cigarette smoking status, and oral contraceptive use