Table 3.

Absolute density: Distribution of breast cancer risk factors by quintiles of threshold and volumetric methods

Threshold method, absolute densityVolumetric method, absolute density
1 (N = 74)2 (N = 74)3 (N = 74)4 (N = 74)5 (N = 74)Ptrend1 (N = 74)2 (N = 74)3 (N = 74)4 (N = 74)5 (N = 74)Ptrend
Age at examination (mean), y55.254.353.954.352.0<0.00154.054.154.053.853.90.79
BMI (mean), kg/m228.526.324.424.823.6<0.00122.723.825.626.828.9<0.001
Age at menarche (mean), y12.713.213.213.313.20.0313.313.113.313.013.00.21
Nulliparous, %14.916.229.712.233.80.0320.326.016.021.623.00.94
Number of children (median)1.81.81.51.91.40.141.71.61.81.61.70.15
Age at first delivery (mean)a, y24.724.626.326.328.1<0.00125.825.426.026.825.30.85
Postmenopausal, %62.258.156.843.233.8<0.00144.657.556.044.651.40.97
Age at menopause (mean),by47.848.747.149.649.60.2045.749.348.747.649.90.04
Ever HT use, %32.927.433.831.130.10.9224.330.628.038.434.20.11
Ever pill use, %86.391.987.890.586.50.9387.889.090.791.883.80.64
First-degree family history of breast cancer, %14.920.317.614.914.90.6920.316.417.314.913.50.27
  • aParous women only.

  • bPostmenopausal women only.