Table 4.

Associations of percent and absolute dense volume with breast cancer risk

HR (95% CI)
N/casesCrudeaModel 1aModel 2a
Percent dense volume (in quartiles)
 Q1 (<5.3)10,276/37Ref. (1.00)Ref. (1.00)Ref. (1.00)
 Q2 (5.3–7.6)10,275/661.84 (1.23–2.75)2.17 (1.42–3.31)2.13 (1.40–3.26)
 Q3 (7.7–11.7)10,276/481.53 (0.99–2.36)2.01 (1.24–3.24)1.90 (1.17–3.07)
 Q4 (>11.7)10,275/552.09 (1.35–3.25)3.17 (1.89–5.33)2.93 (1.73–4.96)
P trend0.01<0.001<0.001
Percent dense volume (per SD increase)b41,102/2061.27 (1.10–1.47)1.51 (1.26–1.81)1.46 (1.22–1.76)
Absolute dense volume (in quartiles)
 Q1 (<42)10,276/47Ref. (1.00)Ref. (1.00)Ref. (1.00)
 Q2 (42–56)10,275/330.68 (0.44–1.06)0.69 (0.44–1.08)0.68 (0.43–1.07)
 Q3 (57–77)10,276/551.19 (0.81–1.77)1.21 (0.81–1.80)1.17 (0.78–1.75)
 Q4 (>77)10,275/711.66 (1.14–2.42)1.73 (1.17–2.55)1.63 (1.10–2.42)
P trend0.001<0.0010.002
Absolute dense volume (per SD increase)b41,102/2061.30 (1.13–1.50)1.33 (1.15–1.54)1.30 (1.12–1.51)

NOTE: Model 1: adjusted for age (years) and BMI (kg/m2).

Model 2: adjusted for age (years), BMI (kg/m2), menopausal status (premenopausal, perimenopausal/unknown, postmenopausal), parity and age at first birth (nulliparous, 1 child age at first birth < 25 years, 1 child age at first birth ≥25 years, 2 children age at first birth < 25 years, 2 children age at first birth ≥25 years, ≥3 children age at first birth < 25 years, ≥3 children age at first birth ≥ 25 years), HRT status (never, former, current), benign breast disease (yes vs. no), and family history of breast cancer (yes vs. no). Volumetric percent and absolute dense volumes were derived from the mediolateral oblique view.

  • aCox proportional hazards models stratified by manufacturer.

  • bBased on log-transformed mammographic measures.