Table 3 Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for breast cancer risk associated with body size at age 18Â years
| Â | KARMA | LIBRO1 | Combined | ||||||
|---|---|---|---|---|---|---|---|---|---|
Body size | Number | Age-adjusted OR (95% CI) | Multivariable OR (95% CI)a | Number | Age-adjusted OR (95% CI) | Multivariable OR (95% CI)a | Number | Age-adjusted OR (95% CI) | Multivariable OR (95% CI)b |
Breast cancer overall | |||||||||
 Small | 705 | 1.00 (Reference) | 1.00 (Reference) | 1482 | 1.00 (Reference) | 1.00 (Reference) | 2187 | 1.00 (Reference) | 1.00 (Reference) |
 Medium | 1407 | 0.97 (0.87–1.07) | 0.95 (0.86–1.06) | 2638 | 0.85 (0.79–0.91) | 0.85 (0.79–0.91) | 4045 | 0.89 (0.84–0.94) | 0.88 (0.83–0.94) |
 Large | 160 | 0.79 (0.66–0.96) | 0.78 (0.64–0.94) | 334 | 0.68 (0.59–0.78) | 0.69 (0.60–0.79) | 494 | 0.72 (0.65–0.80) | 0.72 (0.64–0.80) |
  P trend |  | 0.005 | 0.013 |  | <0.001 | <0.001 |  | <0.001 | <0.001 |
Premenopausal breast cancer | |||||||||
 Small | 214 | 1.00 (Reference) | 1.00 (Reference) | 284 | 1.00 (Reference) | 1.00 (Reference) | 498 | 1.00 (Reference) | 1.00 (Reference) |
 Medium | 466 | 1.06 (0.87–1.31) | 1.03 (0.84–1.28) | 545 | 0.82 (0.70–0.97) | 0.80 (0.68–0.94) | 1011 | 0.91 (0.80–1.03) | 0.88 (0.78–1.00) |
 Large | 52 | 0.70 (0.49–1.00) | 0.66 (0.46–0.95) | 84 | 0.66 (0.50–0.86) | 0.62 (0.47–0.81) | 136 | 0.67 (0.54–0.83) | 0.63 (0.51–0.78) |
  P trend |  | 0.190 | 0.043 |  | <0.001 | <0.001 |  | <0.001 | <0.001 |
Postmenopausal breast cancer | |||||||||
 Small | 491 | 1.00 (Reference) | 1.00 (Reference) | 1198 | 1.00 (Reference) | 1.00 (Reference) | 1689 | 1.00 (Reference) | 1.00 (Reference) |
 Medium | 941 | 0.94 (0.83–1.07) | 0.93 (0.82–1.06) | 2093 | 0.83 (0.76–0.91) | 0.84 (0.77–0.91) | 3034 | 0.87 (0.81–0.93) | 0.87 (0.81–0.93) |
 Large | 108 | 0.87 (0.69–1.09) | 0.86 (0.68–1.09) | 250 | 0.67 (0.57–0.78) | 0.69 (0.59–0.81) | 358 | 0.72 (0.63–0.82) | 0.74 (0.64–0.84) |
  P trend |  | 0.065 | 0.142 |  | <0.001 | <0.001 |  | <0.001 | <0.001 |