Table 1.

Comparison of baseline characteristics and mammographic density among women who remained unaffected and women who developed either ER-positive or ER-negative cancers

Characteristic*Women without breast cancer (n = 44,110)Women with ER-positive breast cancer (n = 504)PWomen with ER-positive breast cancer (n = 118)P
Age, mean (SD)53.5 (11.9)57.9 (12.2)<0.00154.9 (12.6)0.21
First-degree relative with cancer (%)15.025.1<0.00124.40.004
Current hormone therapy use (%)22.629.50.00316.70.90
Nulliparity (%)30.536.30.00626.80.96
Premenopausal (%)42.043.30.5941.70.20
BMI, mean (SD)27.1 (6.2)27.2 (6.8)0.7428.4 (7.4)0.02
Race (%)
White52.468.343.8
Asian20.618.2<0.00110.30.07
Latina/Hispanic18.28.5<0.00120.40.73
African American8.63.7<0.00112.50.17
Native American0.200
Mammographic density (%)
BI-RADS 17.22.30.0010.90.034
BI-RADS 244.539.442.0
BI-RADS 340.843.90.00234.20.72
BI-RADS 47.413.1<0.0019.60.048
  • NOTE: All variables are presented as age-adjusted proportions or means. Statistical tests for association with ER-positive and ER-negative cancers are adjusted for age.

  • * All characteristics age-adjusted except for age.

  • Ps for comparison of women with ER-positive breast cancer versus women without breast cancer.

  • Ps for comparison of women with ER-negative breast cancer versus women without breast cancer.