| Control | Case | ||
---|---|---|---|---|
Characteristics | Number | Percentage | Number | Percentage |
Number | 1,395 | Â | 1,351 | Â |
Mean age ± SD, years | 56.1 ± 9.5 |  | 55.0 ± 9.4 |  |
Menopausal status | Â | Â | Â | Â |
   Premenopausal | 347 | 25.3 | 364 | 27.5 |
   Postmenopausala | 1,024 | 74.7 | 962 | 72.5 |
   Unknown | 24 | - | 25 | - |
HT use among postmenopausal women | Â | Â | Â | Â |
   Never used HT | 153 | 15.8 | 112 | 12.4 |
   Current ET use | 277 | 28.7 | 230 | 25.5 |
   Current EPT use | 401 | 41.5 | 468 | 51.9 |
   Former ET or EPT use | 122 | 12.6 | 80 | 8.9 |
   Ever used progestin alone | 13 | 1.3 | 12 | 1.3 |
   Unknown | 58 | - | 60 | - |
Parity/total number of FTPs | Â | Â | Â | Â |
   Nulligravid | 221 | 16.1 | 219 | 16.4 |
   Gravid, nulliparous | 61 | 4.4 | 66 | 4.9 |
   1 FTP | 159 | 11.6 | 174 | 13.0 |
   2 FTPs | 487 | 35.4 | 472 | 35.3 |
   3 FTPs | 274 | 20.0 | 277 | 20.7 |
   4+ FTPs | 172 | 12.5 | 128 | 9.6 |
   Unknown | 21 | - | 15 | - |
Body mass index | Â | Â | Â | Â |
   < 25 kg/m2 | 765 | 54.8 | 778 | 58.9 |
   25 to < 30 kg/m2 | 387 | 27.7 | 384 | 29.1 |
   30+ kg/m2 | 195 | 14.0 | 159 | 12.0 |
   Unknown | 48 | - | 30 | - |
Age at menarche | Â | Â | Â | Â |
   ≤10 years | 100 | 7.3 | 100 | 7.5 |
   11-12 years | 600 | 43.6 | 599 | 44.8 |
   13-14 years | 565 | 41.0 | 542 | 40.6 |
   15-16 years | 102 | 7.4 | 82 | 6.1 |
   17+ years | 10 | 0.7 | 13 | 1.0 |
   Unknown/Never had menarche | 18 | - | 15 | - |
Family history of breast cancer (first-degree relative) | Â | Â | Â | Â |
   No | 1,167 | 86.1 | 1,085 | 82.1 |
   Yes | 189 | 13.9 | 236 | 17.9 |
   Unknown | 39 | - | 30 | - |
History of breast biopsy | Â | Â | Â | Â |
   No | 1,086 | 77.8 | 1,034 | 76.5 |
   Yes | 309 | 22.2 | 317 | 23.5 |
Screening mammograms within last 2 years | Â | Â | Â | Â |
   No | 138 | 10.0 | 146 | 10.9 |
   Yes | 1,241 | 90.0 | 1,193 | 89.1 |
   Unknown | 16 | - | 12 | - |