Table 5.

Risk of breast cancer according to percentage of mammographic density

Categories of percent density (%)
No.P*
0<1010 < 2525 < 5050 < 75≥75
Case19129296442208201,114
Control40217334363150101,114
OR, not adjusted for BMI (95% CI)11.21 (0.7-2.2)1.78 (1.0-3.2)2.45 (1.4-4.4)2.86 (1.6-5.2)4.25 (1.6-11.1)<0.0001
OR, adjusted for BMI (95% CI)11.27 (0.7-2.3)2.00 (1.1-3.6)2.98 (1.7-5.4)3.70 (2.0-6.9)5.86 (2.2-15.6)<0.0001
  • NOTE: Unmatched logistic regression, adjusted for age, age at menarche, age at first birth, parity, number of live births, menopausal status, age at menopause, hormone replacement therapy (ever/never), breast cancer in first-degree relatives (0, 1, 2+), study (NBSS, OBSP, SMPBC), and observation time (≤2, 2-4, and >4 years), not adjusted for BMI.

  • * P value for testing the linear trend.

  • Adjusted only above factors.

  • Adjusted with above factors and BMI.