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Table 1 Characteristics of the study participants at time of joining the cohort

From: The association of polymorphisms in hormone metabolism pathway genes, menopausal hormone therapy, and breast cancer risk: a nested case-control study in the California Teachers Study cohort

  Control Case
Characteristics Number Percentage Number Percentage
Number 1,395   1,351  
Mean age ± SD, years 56.1 ± 9.5   55.0 ± 9.4  
Menopausal status     
   Premenopausal 347 25.3 364 27.5
   Postmenopausala 1,024 74.7 962 72.5
   Unknown 24 - 25 -
HT use among postmenopausal women     
   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     
   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     
   < 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     
   ≤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)     
   No 1,167 86.1 1,085 82.1
   Yes 189 13.9 236 17.9
   Unknown 39 - 30 -
History of breast biopsy     
   No 1,086 77.8 1,034 76.5
   Yes 309 22.2 317 23.5
Screening mammograms within last 2 years     
   No 138 10.0 146 10.9
   Yes 1,241 90.0 1,193 89.1
   Unknown 16 - 12 -
  1. aIncludes perimenopausal women. EPT, estrogen progestin combined therapy; ET, estrogen therapy; FTP, full-term pregnancy; HT, hormone therapy; SD, standard deviation.