Table 1. The demographic and hormone-related characteristics of all recruited women.
| Factors |
Pre-menopause N=503 007 |
Post-menopause N=890 978 |
||||
|---|---|---|---|---|---|---|
| Free of breast cancer N(%) | Prevalence breast cancer N(%) | Incidence breast cancer N(%) | Free of breast cancer N(%) | Prevalence breast cancer N(%) | Incidence breast cancer N(%) | |
| Age at recruitment | ||||||
| <40 | 121 968(24.67) | 141(8.80) | 1702(24.42) | 1005(0.11) | 0(0.00) | 11(0.16) |
| 40–49 | 225 429(45.59) | 450(28.09) | 3962(56.85) | 21 032(2.39) | 39(1.05) | 258(3.67) |
| 50–59 | 147 039(29.74) | 1011(63.11) | 1305(18.73) | 450 445(51.17) | 2236(60.08) | 3772(53.59) |
| 60–69 | 0(0.00) | 0(0.00) | 0(0.00) | 31 8301(36.16) | 1353(36.35) | 2522(35.83) |
| ⩾70 | 0(0.00) | 0(0.00) | 0(0.00) | 89 434(10.16) | 94(2.53) | 476(6.76) |
| BMI | ||||||
| <18.5 | 15 384(3.22) | 36(2.29) | 224(3.34) | 19331(2.46) | 84(2.40) | 103(1.71) |
| 18.5–23.9 | 283 602(59.36) | 936(59.58) | 4161(62.02) | 375 549(47.70) | 1593(45.61) | 2578(42.80) |
| 24–26.9 | 114 707(24.01) | 377(24.00) | 1518(22.63) | 237 766(30.20) | 1093(31.29) | 1939(32.19) |
| 27–29.9 | 43 546(9.11) | 154(9.80) | 562(8.38) | 105 322(13.38) | 490(14.03) | 923(15.32) |
| 30–34.9 | 17 532(3.67) | 62(3.95) | 216(3.22) | 42 716(5.43) | 196(5.61) | 417(6.92) |
| ⩾35 | 2993(0.63) | 6(0.38) | 28(0.42) | 6599(0.84) | 37(1.06) | 63(1.05) |
| Age at menarche | ||||||
| ⩽13 | 134 295(28.32) | 526(33.80) | 2091(31.41) | 159 981(18.65) | 950(25.75) | 1345(19.70) |
| 14 | 138 451(29.19) | 440(28.28) | 2008(30.16) | 189 723(22.12) | 977(26.48) | 1578(23.12) |
| 15 | 98 623(20.80) | 290(18.64) | 1303(19.57) | 173 794(20.26) | 731(19.81) | 1429(20.93) |
| ⩾16 | 102 866(21.69) | 300(19.28) | 1256(18.86) | 334 368(38.95) | 1032(27.97) | 2474(36.24) |
| Birth | ||||||
| No | 22 378(4.57) | 136(8.57) | 399(5.81) | 35 302(4.02) | 306(8.23) | 399(5.70) |
| Yes | 467 736(95.43) | 1451(91.43) | 6471(94.19) | 842 123(95.98) | 3414(91.77) | 6600(94.30) |
| No. of birtha | ||||||
| 1 | 35 762(7.65) | 156(10.75) | 643(9.94) | 33 909(4.03) | 255(7.47) | 315(4.77) |
| 2 | 186 266(39.82) | 653(45.00) | 2884(44.57) | 159 867(18.98) | 989(28.97) | 1318(19.97) |
| ⩾3 | 245 708(52.53) | 642(44.25) | 2944(45.50) | 648 347(76.99) | 2170(63.56) | 4967(75.26) |
| Age at full-term pregnancya | ||||||
| ⩽22 | 92 818(26.33) | 111(18.17) | 1091(19.09) | 328 738(39.86) | 958(28.47) | 2283(35.23) |
| 23–25 | 107 326(30.44) | 181(29.62) | 1642(28.73) | 274 274(33.26) | 1089(32.36) | 2116(32.65) |
| 26–29 | 104 786(29.72) | 202(33.06) | 1914(33.48) | 161 333(19.56) | 885(26.30) | 1459(22.51) |
| ⩾30 | 47 605(13.50) | 117(19.15) | 1069(18.70) | 60 316(7.31) | 433(12.87) | 623(9.61) |
| Breast feedinga | ||||||
| No | 211 953(44.72) | 854(55.17) | 3104(47.58) | 193 792(22.44) | 1382(37.62) | 1626(23.98) |
| Yes | 261 997(55.28) | 694(44.83) | 3420(52.42) | 66 9749(77.56) | 2292(62.38) | 5155(76.02) |
| Family history | ||||||
| No | 472 375(96.52) | 1473(92.41) | 6573(95.27) | 844 882(96.77) | 3444(92.71) | 6633(95.03) |
| Yes | 17045(3.48) | 121(7.59) | 326(4.73) | 28220(3.23) | 271(7.29) | 347(4.97) |
| Hormone therapy | ||||||
| No | 99 652(91.75) | 845(92.86) | 508(88.04) | 366 358(81.96) | 2444(82.71) | 1718(77.11) |
| Yes | 8963(8.25) | 65(7.14) | 69(11.96) | 80 664(18.04) | 511(17.29) | 510(22.89) |
a
Among parous women.