Table 1.

Comparisons of demographic characteristics and known breast cancer risk factors in patients diagnosed with breast cancer or BBD

All BC cases (n = 1,459)Selected BC cases (n = 64)BBD (n = 68)P*P
Age (mean), y47.947.643.20.70<0.01
Education ≥high school, %45.250.051.50.510.87
Age at menarche (mean), y14.514.614.60.520.86
Postmenopause, %34.533.37.50.88<0.01
Body mass index (mean)23.524.323.40.060.12
Waist-to-hip ratio (mean)0.810.810.790.670.06
Physical activities, %18.718.816.20.880.70
Family history of BC among first-degree relatives3.76.31.50.450.15
  • Abbreviation: BC, breast cancer.

  • * The P values were for the comparisons between selected 64 breast cancer cases and the entire 1,459 breast cancer cases in the parent study and derived from the z test.

  • The P values were for the comparisons between selected 64 breast cancer cases and 68 BBD subjects and derived from the t test for continuous variables and the χ2 test for categorical variables.