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. Author manuscript; available in PMC: 2015 Nov 1.
Published in final edited form as: Cancer Epidemiol Biomarkers Prev. 2014 Aug 19;23(11):2338–2348. doi: 10.1158/1055-9965.EPI-14-0257

Table 2.

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

Characteristic N Percent mammographic density measures
Absolute mammographic density measures
% FGV PD FGV (cm3) DA (cm2)
β SE p-value β SE p-value β SE p-value β SE p-value
Age at mammogram (years)
 39–45 81 ref ref ref ref
 45–49 109 −0.04 0.19 0.84 0.03 0.25 0.8977 0.21 0.50 0.68 0.14 0.31 0.64
 50–54 102 −0.36 0.19 0.06 −0.14 0.25 0.5864 −0.24 0.51 0.63 0.14 0.31 0.65
 55–59 68 −1.14 0.21 <.0001 −0.86 0.28 0.002 −1.55 0.56 0.006 −0.64 0.34 0.07
 60–65 53 −0.91 0.23 <.0001 −1.06 0.30 0.0005 −0.66 0.61 0.28 −0.76 0.37 0.04
 p-value for trend <.0001 <.0001 0.01 0.0065
Race
 White, non-Hispanic 383 ref ref ref ref
 Other 30 0.50 0.25 0.04 0.80 0.32 0.01 −0.05 0.65 0.94 0.56 0.40 0.16
Education level
 <High school or high school grad 63 ref ref ref ref
 College/Graduate school degree 347 0.19 0.18 0.28 0.44 0.23 0.06 0.56 0.47 0.23 0.56 0.28 0.048
Height (inches)**
 51–62 113 ref ref ref ref
 63–65 168 0.04 0.20 0.85 0.20 0.25 0.41 −0.87 0.43 0.04 −0.04 0.26 0.88
 66–72.5 132 0.11 0.22 0.62 0.43 0.26 0.10 −0.79 0.45 0.08 0.09 0.27 0.74
 p-value for trend 0.62 0.09 0.09 0.72
Weight (pounds)**
 90–136 134 ref ref ref ref
 137–166 141 −1.10 0.16 <.0001 −1.07 0.21 <.0001 1.25 0.42 0.003 −0.17 0.25 0.496
 167–338.5 138 −2.61 0.16 <.0001 −2.62 0.21 <.0001 1.62 0.42 0.0001 −1.02 0.25 <.0001
 p-value for trend <.0001 <.0001 0.0001 <.0001
Body mass index, kg/m2
 <25 196 ref ref ref ref
 25-<30 105 −1.40 0.16 <.0001 −1.31 0.21 <.0001 1.32 0.42 0.002 −0.21 0.25 0.41
 30+ 112 −2.52 0.15 <.0001 −2.67 0.20 <.0001 1.79 0.41 <.0001 −1.07 0.25 <.0001
 p-value for trend <.0001 <.0001 <.0001 <.0001
Age at menarche (years)
 ≤12 153 ref ref ref ref
 13 150 0.28 0.15 0.06 0.47 0.19 0.02 0.28 0.39 0.47 0.43 0.24 0.08
 ≥14 104 0.21 0.16 0.19 0.24 0.21 0.25 0.01 0.44 0.97 0.08 0.27 0.75
 p-value for trend 0.15 0.17 0.95 0.65
Parity
 Nulliparous 98 ref ref ref ref
 1 58 0.10 0.22 0.66 0.20 0.28 0.48 0.54 0.57 0.35 0.55 0.35 0.11
 2 164 0.11 0.17 0.52 −0.17 0.22 0.43 0.04 0.43 0.93 −0.03 0.27 0.92
 3+ 92 0.08 0.19 0.66 −0.13 0.25 0.60 −0.62 0.50 0.21 −0.16 0.30 0.61
 p-value for trend 0.59 0.37 0.23 0.39
Age at first birth (years)
 <30 217 ref ref ref ref
 Nulliparous or ≥30 195 0.14 0.13 0.30 0.20 0.17 0.24 0.41 0.34 0.23 0.13 0.21 0.53
 p-value for trend 0.13 0.87 0.44 0.54
Oral contraceptives
 Never 58 ref ref ref ref
 Former 335 −0.11 0.18 0.55 −0.02 0.23 0.92 −0.32 0.47 0.49 −0.17 0.29 0.55
 Current 14 0.28 0.39 0.46 0.36 0.50 0.48 0.79 1.02 0.44 0.39 0.62 0.53
Menopausal status
 Premenopausal 250 ref ref ref ref
 Postmenopausal 163 −0.84 0.20 <.0001 −0.79 0.27 0.004 −1.47 0.55 0.007 −0.80 0.33 0.02
Age at menopause (years)
 Premenopausal 250 0.89 0.32 0.006 0.35 0.42 0.40 1.71 0.85 0.04 0.32 0.52 0.53
 ≤45 32 0.23 0.35 0.51 −0.15 0.46 0.74 0.37 0.93 0.69 −0.28 0.57 0.62
 46–49 34 0.11 0.34 0.75 −0.62 0.45 0.17 0.12 0.92 0.89 −0.86 0.56 0.13
 50–52 23 ref ref ref ref
 53+ 21 0.11 0.39 0.77 −0.46 0.51 0.37 0.53 1.04 0.61 −0.49 0.63 0.44
 Postmenopausal, age unknown 53 −0.08 0.32 0.81 −0.61 0.42 0.15 0.34 0.85 0.69 −0.51 0.52 0.32
Menopausal hormone therapy
 Never 303 ref ref ref ref
 Former 77 0.05 0.18 0.79 −0.05 0.23 0.83 −0.78 0.46 0.10 −0.27 0.28 0.34
 Current 20 0.38 0.31 0.23 0.004 0.41 0.99 −0.56 0.82 0.49 −0.43 0.50 0.39
 Missing/Unknown 13 0.39 0.37 0.29 0.67 0.48 0.16 1.16 0.97 0.23 0.85 0.59 0.15
Cigarette smoking, 100+ cigarettes/lifetime
 Never 203 ref ref ref ref
 Ever 201 −0.30 0.13 0.02 −0.45 0.17 0.008 0.22 0.34 0.52 −0.21 0.21 0.31
Breast biopsy prior to enrollment
 Never 269 ref ref ref ref
 Ever 140 0.32 0.14 0.02 0.62 0.18 0.0004 0.55 0.36 0.12 0.71 0.22 0.001
Family history of breast cancer in a 1st degree female relative
 0 305 ref ref ref ref
 1+ 103 0.18 0.15 0.23 0.08 0.19 0.69 0.56 0.39 0.15 0.11 0.24 0.65
Lump at the time of mammography
 No 357 ref ref ref ref
 Yes 52 0.23 0.19 0.24 0.64 0.25 0.01 −0.76 0.51 0.14 0.49 0.31 0.12
Reason for mammography
 Screening 326 ref ref ref ref
 Short-interval follow-up 21 −0.05 0.29 0.87 0.61 0.38 0.11 −0.42 0.77 0.58 0.61 0.47 0.20
 Evaluation of breast problem 61 0.13 0.18 0.46 0.51 0.24 0.03 −0.61 0.48 0.20 0.45 0.29 0.12
BI-RADS breast density
 I (entirely fat) 56 ref ref ref ref
 II (scattered densities) 183 0.51 0.17 0.002 1.60 0.18 <.0001 0.64 0.51 0.21 2.15 0.26 <.0001
 III (heterogeneously dense) 131 1.47 0.18 <.0001 3.35 0.20 <.0001 1.56 0.56 0.01 3.72 0.29 <.0001
 IV (extremely dense) 33 2.81 0.25 <.0001 4.79 0.27 <.0001 2.85 0.78 0.0003 4.67 0.39 <.0001
 p-value for trend <.0001 <.0001 <.0001 <.0001
Final BI-RADS mammography assessment
 3 (probably benign finding) 26 ref ref ref ref
 4 (suspicious abnormality) 363 0.29 0.26 0.27 0.23 0.34 0.51 0.73 0.68 0.29 0.35 0.42 0.40
 5 (highly suggestive of malignancy) 23 −0.03 0.37 0.93 0.27 0.48 0.58 0.26 0.98 0.79 0.33 0.60 0.58
 p-value for trend 0.96 0.53 0.68 0.50
Biopsy type
 Ultrasound-guided 195 ref ref ref ref
 Stereotactic-guided 208 0.16 0.13 0.23 0.13 0.17 0.46 0.36 0.34 0.29 0.15 0.21 0.49
 Both 7 0.41 0.50 0.41 0.20 0.66 0.76 2.63 1.32 0.047 0.88 0.81 0.28
Biopsy laterality
 Left 203 ref ref ref ref
 Right 210 −0.25 0.13 0.05 0.21 0.17 0.20 −1.42 0.33 <.0001 0.12 0.21 0.55
Pathologic diagnosis
 Benign 141 ref ref ref ref
 Proliferative 171 0.10 0.15 0.51 −0.06 0.19 0.75 0.28 0.39 0.47 −0.01 0.24 0.96
 Proliferative with atypia 32 0.55 0.26 0.03 0.81 0.33 0.02 0.81 0.68 0.24 0.71 0.41 0.09
 In situ 34 −0.09 0.25 0.73 0.21 0.33 0.53 0.13 0.67 0.85 0.20 0.41 0.63
 Invasive breast cancer 35 0.06 0.25 0.81 0.06 0.32 0.86 0.60 0.65 0.36 0.23 0.40 0.56
 p-value for trend 0.71 0.35 0.35 0.32

BI-RADS, Breast Imaging Reporting and Data System; BMI, body mass index; DA, dense area; FGV, fibroglandular volume; PD, percent density

*

Mammographic density measures were square-root transformed.

**

Tertiles of height and weight are presented.