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Table 2 Baseline characteristics of breast cancer cases and controls.

From: SNP-SNP interactions in breast cancer susceptibility

  Cases Controls Pvalue#
  n % n %  
Overall 398   372   
Age*      
≤ 40 79 19.8 69 18.6 0.08
41–45 106 26.6 98 26.4  
46–50 144 36.2 113 30.4  
51–55 69 17.3 91 24.5  
Missing 0 - 1 -  
Mean (SD) 44.8 (6.2) 45.2 (6.6) 0.37
BMI      
<18.5 7 2.2 4 1.1 0.05
18.5 – 25 178 55.1 166 46.0  
25 – 30 81 25.1 116 32.1  
> 30 57 17.6 75 20.8  
Missing 75 - 11 -  
Mean (SD) 25.7 (5.4) 26.3 (5.5) 0.14
Education      
Up to high school 122 35.4 101 27.2 0.06
Technical school 27 7.8 34 9.2  
Some college/University 196 56.8 236 63.4  
Missing 53 - 1 -  
Smoking status      
Ever smoked 184 53.2 209 56.3 0.40
Never smoked 162 46.8 162 43.7  
Missing 52 - 1 -  
Family History      
Yes 86 21.6 34 9.2 <10-5
No 312 78.4 337 90.8  
Missing 0 - 1 -  
Menopausal status      
Pre-menopausal 296 84.0 261 82.1 0.42
Post-menopausal 56 16.0 57 17.9  
Missing 46 - 54 -  
Age at menarche      
Age ≤ 12 154 45.2 177 48.1 0.43
Age > 12 187 54.8 191 51.9  
Missing 57 - 4 -  
Age period stopped      
Pre-menopausal 296 84.6 261 82.1 0.68
Age ≤ 49 39 11.1 42 13.2  
Age > 49 15 4.3 15 4.7  
Missing 48 - 54 -  
Parity (# of live births)      
Nulliparous 68 19.6 63 17.0 0.85
1 child 56 16.1 57 15.4  
2 children 145 41.8 157 42.3  
≥ 3 children 78 22.4 94 25.3  
Missing 51 - 1 -  
Age at 1 st live birth      
Nulliparous 68 19.7 63 17.0 0.63
≤ 24 years 126 36.4 136 36.7  
> 24 years 152 43.9 172 46.4  
Missing 52 - 1 -  
  1. *Age of first breast cancer diagnosis for cases and age at interview for controls
  2. Uncertain or missing data
  3. Women with first-degree relatives with breast cancer
  4. # χ2 test for categorical variables or Student's t test (equal variance) for continuous variables