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Table 1 Characteristics of Polish Breast Cancer Study participants (n = 4,194)

From: Genetic variation in PRL and PRLR, and relationships with serum prolactin levels and breast cancer risk: results from a population-based case-control study in Poland

Characteristic Case Control P valuea
  Number Percentage Number Percentage  
Age      
   Less than 40 years 80 4 92 4  
   40-49 years 501 26 554 25  
   50-59 years 668 34 759 34  
   60-69 years 508 26 588 26  
   At least 70 years 208 11 236 11  
Menopausal status      
   Premenopausal 521 27 686 31 <0.01
   Postmenopausal 1,444 73 1,543 69  
Parity      
   Nulliparous 283 14 248 11 <0.01
   Parous 1,682 86 1,981 89  
Breastfeedingb      
   0 months 353 21 368 19 0.03
   Less than 12 months 939 56 1,078 54  
   12 to 23 months 255 15 336 17  
   At least 24 months 135 8 199 10  
Age at menarche      
   Not more than 12 years 562 29 497 23 <0.01
   13 years 427 22 516 23  
   14 years 520 27 615 28  
   15 years 208 11 253 11  
   At least 16 years 233 12 322 15  
Body mass index      
   Less than 25 kg/m2 732 37 705 32 <0.01
   25 to less than 30 kg/m2 696 35 812 36  
   At least 30 kg/m2 535 27 709 32  
Oral HT usec      
   Never 1,106 82 1,284 88 <0.01
   Current 120 9 68 5  
   Recent 64 5 25 2  
   Past 62 5 83 6  
Alcohol drinks per week      
   Never drinker 1,254 65 1,464 67 0.11
   0 to less than 1 184 10 206 9  
   1 to less than 3 282 15 289 13  
   3 to less than 5 71 4 97 4  
   At least 5 137 7 121 6  
Family history of breast cancerd      
   No 1,766 90 2,101 94 <0.01
   Yes 198 10 128 6  
  1. aPearson chi-square test P value. bParous women only. cHT, hormone therapy, postmenopausal women only. dMother, sister, daughter, excludes half-sisters.