Table 1.

Comparisons of cases and controls on demographics and selected breast cancer risk factors (Shanghai Breast Cancer Study, 1996-1999)

CharacteristicsCases (n = 1,459)Controls (n = 1,556)P
Age47.93 ± 7.9947.25 ± 8.790.24
Education(%)
    No formal education3.635.46
    Elementary school8.508.42
    Middle + high school74.375.4
    Profession, college and above13.610.70.012
Breast cancer in first-degree relatives (%)3.72.40.045
Ever had breast fibroadenoma (%)9.65.0<0.001
Nulliparous (%)5.13.90.126
Age at first live birth (y)26.7 ± 4.226.2 ± 3.9<0.01
Menarcheal age (y)14.5 ± 1.614.7 ± 1.7<0.01
Postmenopausal (%)34.536.20.321
Menopausal age (y)*48.1 ± 4.647.4 ± 4.90.02
  • * Among postmenopausal women only.