Table 1.

Comparison of cases and controls by selected descriptive characteristics, Shanghai Breast Cancer Study, 1996-1998

Subject characteristicCases (n = 1,132)Controls (n = 1,222)P*
Age (y), mean ± SD47.6 ± 8.047.2 ± 8.70.20
Education (%)
    Elementary school or below12.314.6
    Middle or high school75.775.4
    College or above12.010.10.11
Breast cancer in first-degree relative (%)3.42.40.12
Ever had breast fibroadenoma (%)9.75.2<0.01
Age at menarche (y)14.5 ± 1.614.7 ± 1.7<0.01
Age at first live birth (y), mean ± SD26.8 ± 4.126.2 ± 3.8<0.01
Postmenopausal (%)33.236.20.13
    Age at menopause (y), mean ± SD48.2 ± 4.647.5 ± 5.00.04
Physically active past 10 y (%)19.225.7<0.01
BMI (kg/m2), mean ± SD23.5 ± 3.423.2 ± 3.40.03
WHR, mean ± SD0.81 ± 0.060.80 ± 0.06<0.01
  • * For χ2 test (categorical variables) or t test (continuous variables).