Table 1 Comparison of demographic characteristics and potential risk factors for breast cancer in two study populations
Population statistics and characteristics | Present study population | Original study populationa | ||
|---|---|---|---|---|
Cases (n = 527) | Controls (n = 904) | Cases (n = 706) | Controls (n = 1,381) | |
Mean age (years) at diagnosis or recruitment | 41.6 | 41.7 | 42.5 | 42.6 |
Mean BMI (kg/m2) | 24.0 | 23.9 | 24.1 | 24.2 |
Mean age (years) at menarche | 13.1 | 13.1 | 13.1 | 13.1 |
Mean age (years) at first full-term pregnancyb | 24.4 | 24.9 | 24.2 | 24.3 |
Population characteristics (%) | ||||
Study region | ||||
Rhein–Neckar–Odenwald | 71.7 | 70.7 | 70.0 | 69.3 |
Freiburg | 28.3 | 29.3 | 30.0 | 30.7 |
Marital statusc | ||||
Single | 9.3 | 9.8 | 7.8 | 8.4 |
Married/with partner | 81.0 | 80.0 | 81.2 | 78.3 |
Widowed, divorced or separated | 9.7 | 10.2 | 10.9 | 13.2 |
Nationality | ||||
German | 91.8 | 97.0 | 91.2 | 95.8 |
Non-German | 8.2 | 3.0 | 8.8 | 4.2 |
Educational level | ||||
Low | 13.5 | 11.7 | 14.7 | 14.2 |
Intermediate | 63.7 | 60.7 | 63.3 | 60.3 |
High | 22.8 | 27.6 | 22.0 | 25.5 |
Parity | ||||
0 | 23.5 | 22.0 | 21.7 | 20.8 |
1 | 27.7 | 24.1 | 29.0 | 24.5 |
2 | 39.5 | 37.5 | 38.5 | 38.0 |
3+ | 9.3 | 16.4 | 10.8 | 16.7 |
Oral contraceptive used | ||||
No | 16.1 | 19.7 | 18.1 | 19.8 |
Yes | 83.9 | 80.1 | 81.9 | 80.0 |
Breastfeedingb | ||||
Never | 28.8 | 26.5 | 31.3 | 29.2 |
Ever | 71.2 | 73.5 | 68.7 | 70.8 |
First-degree family history of breast cancer | ||||
No | 87.7 | 94.7 | 87.7 | 94.9 |
Yes | 12.3 | 5.3 | 12.3 | 5.1 |
Daily average alcohol intake | ||||
0 g | 20.7 | 16.4 | 21.7 | 17.3 |
1–18 g | 65.6 | 74.5 | 63.8 | 74.1 |
>18 g | 13.7 | 9.1 | 14.5 | 8.7 |