Table 3 Expected and observed number of breast cancer in test subcohort of China Kadoorie Biobank (CKB) and Shanghai Women’s Health Study (SWHS)
| Â | Test subcohort of CKB | SWHS | ||||
|---|---|---|---|---|---|---|
E | O | E/O (95% CI) | E | O | E/O (95% CI) | |
Overall | 760 | 751 | 1.01 (0.94–1.09) | 1320 | 1409 | 0.94 (0.89–0.99) |
Age at enrollment, years | ||||||
 < 50 | 372 | 357 | 1.04 (0.94–1.16) | 735 | 688 | 1.07 (0.99–1.15) |
 50–59 | 277 | 256 | 1.08 (0.96–1.23) | 377 | 394 | 0.96 (0.87–1.06) |
 ≥ 60 | 111 | 138 | 0.81 (0.68–0.96) | 208 | 327 | 0.64 (0.57–0.71) |
Residence | ||||||
 Rural | 351 | 267 | 1.31 (1.17–1.49) | -- | -- | -- |
 Urban | 409 | 484 | 0.85 (0.77–0.93) | 1320 | 1409 | 0.94 (0.89–0.99) |
Highest education | ||||||
 Primary school or lower | 333 | 299 | 1.11 (0.99–1.25) | 143 | 195 | 0.73 (0.64–0.85) |
 Middle school | 218 | 212 | 1.03 (0.90–1.18) | 487 | 503 | 0.97 (0.89–1.06) |
 High school or higher | 209 | 240 | 0.87 (0.77–0.99) | 690 | 711 | 0.97 (0.90–1.05) |
BMI, kg/m2 | ||||||
 < 18.5 | 21 | 17 | 1.21 (0.76–2.08) | 34 | 38 | 0.90 (0.66–1.27) |
 18.5–23.9 | 340 | 326 | 1.04 (0.94–1.17) | 627 | 660 | 0.95 (0.88–1.03) |
 24.0–27.9 | 282 | 282 | 1.00 (0.89–1.13) | 477 | 512 | 0.93 (0.85–1.02) |
 ≥ 28 | 117 | 126 | 0.93 (0.78–1.12) | 181 | 199 | 0.91 (0.79–1.05) |
Height, cm | ||||||
 < 150.2 | 139 | 122 | 1.14 (0.96–1.38) | 85 | 119 | 0.71 (0.59–0.86) |
 150.2–154.1 | 172 | 151 | 1.14 (0.97–1.35) | 185 | 199 | 0.93 (0.81–1.07) |
 154.2–158.1 | 204 | 217 | 0.94 (0.82–1.08) | 360 | 387 | 0.93 (0.84–1.03) |
 ≥ 158.2 | 245 | 261 | 0.94 (0.83–1.06) | 690 | 704 | 0.98 (0.91–1.06) |
No. of first-degree relatives diagnosed with overall cancer | ||||||
 0 | 607 | 573 | 1.06 (0.98–1.15) | 926 | 1023 | 0.91 (0.85–0.96) |
 1 | 126 | 144 | 0.87 (0.74–1.04) | 316 | 329 | 0.96 (0.86–1.07) |
 ≥ 2 | 27 | 34 | 0.80 (0.57–1.16) | 77 | 57 | 1.35 (1.04–1.78) |
No. of live birth | ||||||
 Nulliparous | 14 | 12 | 1.17 (0.67–2.26) | 52 | 58 | 0.89 (0.69–1.18) |
 1 | 340 | 353 | 0.96 (0.87–1.07) | 852 | 822 | 1.04 (0.97–1.11) |
 ≥2 | 406 | 386 | 1.05 (0.95–1.17) | 416 | 529 | 0.79 (0.72–0.86) |
Age at menarche, years | ||||||
 < 12 | 54 | 60 | 0.90 (0.70–1.19) | 118 | 105 | 1.12 (0.93–1.37) |
 13–14 | 244 | 266 | 0.92 (0.81–1.04) | 556 | 567 | 0.98 (0.90–1.07) |
 15–16 | 279 | 275 | 1.01 (0.90–1.15) | 481 | 553 | 0.87 (0.80–0.95) |
 ≥ 17 | 183 | 150 | 1.22 (1.04–1.45) | 164 | 184 | 0.89 (0.77–1.04) |