Table 2

Baseline characteristics of breast cancer cases and controls.

Cases
 Controls
 P value#


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 1st 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
 -

*Age of first breast cancer diagnosis for cases and age at interview for controls

†Uncertain or missing data

‡ Women with first-degree relatives with breast cancer

# χ2 test for categorical variables or Student's t test (equal variance) for continuous variables

Onay et al. BMC Cancer 2006 6:114   doi:10.1186/1471-2407-6-114