Table 2

Median (P25–P75a; no. of subjects) percent mammographic density in breast cancer cases and controls by ethnic group and age

CasesControlsTwo-sided Pb
White
 <Age 50 years46.02 (29.60–61.60; 154)42.29 (20.41–52.17; 109)0.04
 ≥Age 50 years32.48 (20.04–51.07; 126)20.41 (7.52–38.30; 118)0.0002
African American
 <Age 50 years42.41 (23.29–53.39; 103)27.29 (13.24–55.98; 67)0.20
 ≥Age 50 years24.02 (7.33–40.14; 96)18.70 (4.09–35.45; 82)0.17
Asian American
 <Age 50 years52.01 (34.23–64.80; 67)43.85 (37.52–57.03; 37)0.29
 ≥Age 50 years35.82 (21.43–46.38; 76)24.18 (10.99–40.05; 30)0.04
  • a P25, 25th percentile; P75, 75th percentile.

  • b Wilcoxon test.