Table 4

ORs and 95% CIs of breast cancer per 10% increase in percent mammographic density or per decile of absolute density in breast cancer cases and controls by ethnic group and age

GroupsPercent densityAbsolute density
Adjusted ORaAdjusted 95% CIaAdjusted ORaAdjusted 95% CIa
By age at mammography (yr)
 <501.080.98–1.191.110.99–1.26
 ≥501.241.11–1.381.201.05–1.38
 Test of effect modification by ageAdjusted two-sided P = 0.05aAdjusted two-sided P = 0.45a
By race and age at mammography (yr)
 White
  <501.100.96–1.261.110.92–1.33
  ≥501.241.05–1.451.311.04–1.65
 African American
  <501.080.90–1.291.120.92–1.36
  ≥501.130.94–1.351.040.85–1.26
 Asian American
  <501.100.84–1.451.260.87–1.82
  ≥501.591.09–2.321.701.02–2.84
  • a Adjusted for ethnicity, age at mammography, BMI, age at menarche, breast cancer family history, number of full-term pregnancies, age at first full-term pregnancy as well as menopausal status and HRT use in women age ≥50 years and in the test of effect modification.