Table 2.

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

Threshold method, percent densityVolumetric method, percent density 
(N = 74)(N = 74)(N = 74)(N = 74)(N = 74)Ptrend(N = 74)(N = 74)(N = 74)(N = 74)(N = 74)Ptrend
Age at examination (mean), y55.254.354.354.352.0<0.00154.<0.79
BMI (mean), kg/m228.326.324.424.823.6<0.00122.723.825.626.828.9<0.001
Age at menarche (mean), y12.713.213.213.313.20.0313.313.113.313.213.00.21
Nulliparous, %14.916.229.712.233.80.0320.326.016.021.623.00.94
Number of children (median)
Age at first delivery (mean),a y24.524.626.326.328.1<0.00125.825.426.026.825.3<0.85
Postmenopausal, %<0.00144.657.556.044.651.4<0.001
Age at menopause (mean),b y47.848.747.149.646.60.2045.749.348.747.649.90.89
Ever HT use, %32.924.433.831.130.10.9224.330.628.038.434.20.43
Ever pill use, %86.391.987.890.586.50.9387.889.090.791.883.80.25
First-degree family history of breast cancer, %14.920.317.614.914.90.6920.316.417.314.913.50.77
  • aParous women only.

  • bPostmenopausal women only.