Table 3.
Adjusteda odds ratio (OR) and 95% confidence interval (CI) for breast cancer overall, triple negative breast cancer, and luminal-like subtype associated with BMI in premenopausal white women and premenopausal African-American women
| All cases | Triple negative (ER–/PR–/HER2–) | Luminal-like (ER+ and/or PR+) | ||||
|---|---|---|---|---|---|---|
| Number | OR (95% CI) | Number | OR (95% CI) | Number | OR (95% CI) | |
| Premenopausal white women | ||||||
| BMI at age 18 years, kg/m2 | ||||||
| < 20.0 | 946 | Referent | 108 | Referent | 553 | Referent |
| 20.0–24.9 | 793 | 1.01 (0.84–1.22) | 91 | 0.92 (0.66–1.30) | 470 | 1.03 (0.83–1.28) |
| ≥ 25.0 | 121 | 0.76 (0.53–1.10) | 12 | 0.53 (0.26–1.09) | 64 | 0.73 (0.47–1.13) |
| Per 5 kg/m2 increase | 0.86 (0.73–1.02) | 0.61 (0.44–0.86) | 0.87 (0.71–1.06) | |||
| P value | 0.08 | 0.004 | 0.16 | |||
| P value for homogeneity of slope coefficients between two subtypes = 0.04 | ||||||
| Recent BMI, kg/m2 | ||||||
| < 25.0 | 1274 | Referent | 136 | Referent | 754 | Referent |
| 25.0–29.9 | 373 | 0.87 (0.69–1.10) | 51 | 1.30 (0.87–1.93) | 205 | 0.78 (0.59–1.02) |
| ≥ 30.0 | 213 | 0.72 (0.53–0.97) | 24 | 1.00 (0.57–1.75) | 128 | 0.71 (0.50–1.01) |
| Per 5 kg/m2 increase | 0.95 (0.86–1.05) | 1.12 (0.94–1.34) | 0.94 (0.83–1.06) | |||
| P value | 0.32 | 0.19 | 0.28 | |||
| P value for homogeneity of slope coefficients between two subtypes = 0.04 | ||||||
| Premenopausal African-American women | ||||||
| BMI at age 18 years, kg/m2 | ||||||
| < 20.0 | 241 | Referent | 52 | Referent | 103 | Referent |
| 20.0–24.9 | 274 | 0.98 (0.72–1.33) | 53 | 0.92 (0.56–1.50) | 107 | 0.90 (0.61–1.35) |
| ≥ 25.0 | 52 | 0.66 (0.40–1.13) | 13 | 0.71 (0.31–1.65) | 19 | 0.60 (0.29–1.24) |
| Per 5 kg/m2 increase | 0.79 (0.62–1.00) | 0.78 (0.54–1.15) | 0.74 (0.54–1.03) | |||
| P value | 0.05 | 0.21 | 0.07 | |||
| P value for homogeneity of slope coefficients between two subtypes = 0.80 | ||||||
| Recent BMI, kg/m2 | ||||||
| < 25.0 | 271 | Referent | 58 | Referent | 114 | Referent |
| 25.0–29.9 | 160 | 0.92 (0.66–1.29) | 29 | 0.79 (0.45–1.37) | 64 | 0.93 (0.60–1.44) |
| ≥ 30.0 | 136 | 1.02 (0.68–1.53) | 31 | 1.09 (0.58– 2.05) | 51 | 0.94 (0.55–1.59) |
| Per 5 kg/m2 increase | 1.08 (0.92–1.25) | 1.13 (0.90–1.43) | 1.04 (0.85–1.28) | |||
| P value | 0.35 | 0.30 | 0.69 | |||
| P value for homogeneity of slope coefficients between two subtypes = 0.53 | ||||||
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 mutual adjustment of BMI at age 18 years and recent BMI and with adjustment for source study, study site, 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