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Table 1 Distribution of reproductive risk factors according to the five surrogate BC subtypes

From: Reproductive profiles and risk of breast cancer subtypes: a multi-center case-only study

   All BC subtypes N = 11,328 (100.0%) Luminal A-like N = 5914 (52.2%) Luminal B-like N = 1553 (13.7%) Luminal HER2-like N = 1509 (13.3%) HER2-like N = 841 (7.4%) TNBC N = 1511 (13.3%)
N % N % N % N % N % N %
Age at breast cancer diagnosis, years Mean/median 56.0/56.0   57.6/57.0   56.9/57.0   52.6/52.0   52.9/53.0   53.8/54.0  
<41 1077 9.5% 328 5.5% 139 9.0% 247 16.4% 120 14.3% 243 16.1%
41–50 2759 24.4% 1369 23.1% 367 23.6% 455 30.2% 226 26.9% 342 22.6%
51–60 51-60y 30.4% 1842 31.1% 424 27.3% 406 26.9% 287 34.1% 481 31.8%
>60 4052 35.8% 2375 40.2% 623 40.1% 401 26.6% 208 24.7% 445 29.5%
Menopausal status Pre/peri 3796 33.5% 1797 30.4% 505 32.5% 612 40.6% 316 37.6% 566 37.5%
Post 7075 62.5% 3886 65.7% 979 63.0% 835 55.3% 484 57.6% 891 59.0%
Unknown 457 4.0% 231 3.9% 69 4.4% 62 4.1% 41 4.9% 54 3.6%
Parity (>/=24 week-pregnancies, n) 0 1746 15.4% 898 15.2% 266 17.1% 242 16.0% 135 16.1% 205 13.6%
1 2062 18.2% 1052 17.8% 302 19.4% 285 18.9% 147 17.5% 276 18.3%
2 4238 37.4% 2238 37.8% 547 35.2% 579 38.4% 302 35.9% 572 37.9%
3 2102 18.6% 1117 18.9% 264 17.0% 270 17.9% 165 19.6% 286 18.9%
4 or more 1180 10.4% 609 10.3% 174 11.2% 133 8.8% 92 10.9% 172 11.4%
Age at menarche, years Mean/median 13.2/13.0   13.2/13.0   13.2/13.0   13.3/13.0   13.4/13.0   13.2/13.0  
<12 1369 13.3% 748 13.8% 186 13.5% 163 12.0% 82 11.1% 190 13.8%
12–13 2104 20.5% 1066 19.7% 308 22.4% 289 21.3% 151 20.4% 290 21.0%
13–14 2578 25.1% 1359 25.1% 318 23.1% 347 13.3% 188 25.3% 366 26.5%
>14 4227 41.1% 2249 41.5% 563 40.9% 561 13.3% 321 43.3% 533 38.7%
Missing 1050   492   178   149   99   132  
Age at FFTP, years Mean/median 25.1/24.0   25.0/24.0   25.3/25.0   25.6/25.0   25.6/25.0   24.7/24.0  
<20 822 10.9% 453 11.2% 98 10.5% 89 9.2% 43 8.1% 139 13.2%
20–25 2948 39.1% 1613 39.8% 353 38.0% 340 35.0% 200 37.8% 442 42.1%
25–30 2417 32.1% 1292 31.8% 300 32.3% 344 35.4% 184 34.8% 297 28.3%
>30 1351 17.9% 699 17.2% 179 19.2% 198 20.4% 102 19.3% 173 16.5%
Missing 2044   1857   623   538   312   460  
  1. BC breast cancer, HER2 human epidermal growth factor receptor-2, TNBC triple negative breast cancer, Pre/peri premenopausal/perimenopausal, FFTP first full-term pregnancy