Table 2.

Age- and BMI-adjusted linear regression results for the association between participant characteristics and volume and area mammographic density measuresa, The BREAST Stamp Project, 2007–2010 (n = 413)

Percent mammographic density measuresAbsolute mammographic density measures
% FGVPDFGV (cm3)DA (cm2)
CharacteristicNβSEPβSEPβSEPβSEP
Age at mammogram (years)
 39–4481Ref.Ref.Ref.Ref.
 45–49109−0.040.190.840.030.250.900.210.500.680.140.310.64
 50–54102−0.360.190.06−0.140.250.59−0.240.510.630.140.310.65
 55–59681.140.21<0.00010.860.280.0021.550.560.006−0.640.340.07
 60–65530.910.23<0.00011.060.300.0005−0.660.610.280.760.370.04
P value for trend<0.0001<0.00010.010.0065
Race
 White, non-Hispanic383Ref.Ref.Ref.Ref.
 Other300.500.250.040.800.320.01−0.050.650.940.560.400.16
Education level
 <High school or high school grad63Ref.Ref.Ref.Ref.
 College/graduate school degree3470.190.180.280.440.230.060.560.470.230.560.280.048
Height (inches)b
 51–62113Ref.Ref.Ref.Ref.
 63–651680.040.200.850.200.250.410.870.430.04−0.040.260.88
 66–72.51320.110.220.620.430.260.10−0.790.450.080.090.270.74
P value for trend0.620.090.090.72
Weight (pounds)b
 90–136134Ref.Ref.Ref.Ref.
 137–1661411.100.16<0.00011.070.21<0.00011.250.420.003−0.170.250.50
 167–338.51382.610.16<0.00012.620.21<0.00011.620.420.00011.020.25<0.0001
P value for trend<0.0001<0.00010.0001<0.0001
BMI, kg/m2
 <25196Ref.Ref.Ref.Ref.
 25–<301051.400.16<0.00011.310.21<0.00011.320.420.002−0.210.250.41
 30+1122.520.15<0.00012.670.20<0.00011.790.41<0.00011.070.25<0.0001
P value for trend<0.0001<0.0001<0.0001<0.0001
Age at menarche (years)
 ≤12153Ref.Ref.Ref.Ref.
 131500.280.150.060.470.190.020.280.390.470.430.240.08
 ≥141040.210.160.190.240.210.250.010.440.970.080.270.75
P value for trend0.150.170.950.65
Parity
 Nulliparous98Ref.Ref.Ref.Ref.
 1580.100.220.660.200.280.480.540.570.350.550.350.11
 21640.110.170.52−0.170.220.430.040.430.93−0.030.270.92
 3+920.080.190.66−0.130.250.60−0.620.500.21−0.160.300.61
P value for trend0.590.370.230.39
Age at first birth (years)
 <30217Ref.Ref.Ref.Ref.
 Nulliparous or 30+1950.140.130.300.200.170.240.410.340.230.130.210.53
P value for trend0.130.870.440.54
Oral contraceptives
 Never58Ref.Ref.Ref.Ref.
 Former335−0.110.180.55−0.020.230.92−0.320.470.49−0.170.290.55
 Current140.280.390.460.360.500.480.791.020.440.390.620.53
Menopausal status
 Premenopausal250Ref.Ref.Ref.Ref.
 Postmenopausal1630.840.20<0.00010.790.270.0041.470.550.0070.800.330.02
Age at menopause (years)
 Premenopausal2500.890.320.0060.350.420.401.710.850.040.320.520.53
 ≤45320.230.350.51−0.150.460.740.370.930.69−0.280.570.62
 46–49340.110.340.75−0.620.450.170.120.920.89−0.860.560.13
 50–5223Ref.Ref.Ref.Ref.
 53+210.110.390.77−0.460.510.370.531.040.61−0.490.630.44
 Postmenopausal, age unknown53−0.080.320.81−0.610.420.150.340.850.69−0.510.520.32
Menopausal hormone therapy
 Never303Ref.Ref.Ref.Ref.
 Former770.050.180.79−0.050.230.83−0.780.460.10−0.270.280.34
 Current200.380.310.230.0040.410.99−0.560.820.49−0.430.500.39
 Missing/unknown130.390.370.290.670.480.161.160.970.230.850.590.15
Cigarette smoking, 100+ cigarettes/lifetime
 Never203Ref.Ref.Ref.Ref.
 Ever2010.300.130.020.450.170.0080.220.340.52−0.210.210.31
Breast biopsy before enrollment
 Never269Ref.Ref.Ref.Ref.
 Ever1400.320.140.020.620.180.00040.550.360.120.710.220.001
Family history of breast cancer in a first-degree female relative
 0305Ref.Ref.Ref.Ref.
 1+1030.180.150.230.080.190.690.560.390.150.110.240.65
Lump at the time of mammography
 No357Ref.Ref.Ref.Ref.
 Yes520.230.190.240.640.250.01−0.760.510.140.490.310.12
Reason for mammography
 Screening326Ref.Ref.Ref.Ref.
 Short-interval follow-up21−0.050.290.870.610.380.11−0.420.770.580.610.470.20
 Evaluation of breast problem610.130.180.460.510.240.03−0.610.480.200.450.290.12
BI-RADS breast density
 I (entirely fat)56Ref.Ref.Ref.Ref.
 II (scattered densities)1830.510.170.0021.600.18<0.00010.640.510.212.150.26<0.0001
 III (heterogeneously dense)1311.470.18<0.00013.350.20<0.00011.560.560.013.720.29<0.0001
 IV (extremely dense)332.810.25<0.00014.790.27<0.00012.850.780.00034.670.39<0.0001
P value for trend<0.0001<0.0001<0.0001<0.0001
Final BI-RADS mammography assessment
 3 (probably benign finding)26Ref.Ref.Ref.Ref.
 4 (suspicious abnormality)3630.290.260.270.230.340.510.730.680.290.350.420.40
 5 (highly suggestive of malignancy)23−0.030.370.930.270.480.580.260.980.790.330.600.58
P value for trend0.960.530.680.50
Biopsy type
 Ultrasound-guided195Ref.Ref.Ref.Ref.
 Stereotactic-guided2080.160.130.230.130.170.460.360.340.290.150.210.49
 Both70.410.500.410.200.660.762.631.320.0470.880.810.28
Biopsy laterality
 Left203Ref.Ref.Ref.Ref.
 Right210−0.250.130.050.210.170.201.420.33<0.00010.120.210.55
Pathologic diagnosis
 Benign141Ref.Ref.Ref.Ref.
 Proliferative1710.100.150.51−0.060.190.750.280.390.47−0.010.240.96
 Proliferative with atypia320.550.260.030.810.330.020.810.680.240.710.410.09
In-situ34−0.090.250.730.210.330.530.130.670.850.200.410.63
 Invasive breast cancer350.060.250.810.060.320.860.600.650.360.230.400.56
P value for trend0.710.350.350.32

NOTE: Beta coefficients with P values <0.05 are presented in bold font. P values for trend are presented in italics.

  • aMammographic density measures were square-root transformed.

  • bTertiles of height and weight are presented.