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Table 2 Association between mammographic measures and breast cancer risk

From: The effect of volumetric breast density on the risk of screen-detected and interval breast cancers: a cohort study

  Cases/person years HR1 (95% CI) HR2 (95% CI) HRinvasive (95% CI)
Volpara density grades
 VDG1 58/46,089 ref NA ref
 VDG2 215/99,086 1.78 (1.33 ; 2.38) NA 1.89 (1.38 ; 2.58)
 VDG3 189/73,207 2.38 (1.76 ; 3.20) NA 2.53 (1.83 ; 3.49)
 VDG4 61/20,314 3.14 (2.17 ; 4.55) NA 3.54 (2.39 ; 5.24)
P trend   <0.001   <0.001
Percent dense volume (in quartiles)
 Q1 (<4.8%) 79/58,411 ref NA ref
 Q2 (4.8–6.4%) 127/61,153 1.57 (1.19 ; 2.08) NA 1.61 (1.19 ; 2.18)
 Q3 (6.4–9.8%) 161/60,499 2.17 (1.65 ; 2.84) NA 2.33 (1.74 ; 3.11)
 Q4 (>9.8%) 156/58,633 2.42 (1.83 ; 3.20) NA 2.52 (1.87 ; 3.40)
P trend   <0.001   <0.001
Percent dense volume (per SD increase)# 523/238,696 1.36 (1.25 ; 1.48) NA 1.38 (1.26 ; 1.51)
Dense volume (VDG-like categories)
 C1 (<39.8 cm3) 69/45,851 ref ref ref
 C2 (39.9– 65.2 cm3) 197/96,827 1.37 (1.04 ; 1.80) 1.53 (1.15 ; 2.05) 1.69 (1.24 ; 2.30)
 C3 (65.3– 110.1 cm3) 176/74,190 1.66 (1.26 ; 2.20) 2.06 (1.52 ; 2.80) 2.27 (1.63 ; 3.14)
 C4 (>110.1 cm3) 81/21,828 2.79 (2.02 ; 3.86) 3.55 (2.49 ; 5.05) 3.66 (2.50 ; 5.36)
P trend   <0.001 <0.001 <0.001
Dense volume (in quartiles)
 Q1 (<42.9 cm3) 91/57,909 ref ref ref
 Q2 (42.9–7.8 cm3) 113/59,364 1.22 (0.93 ; 1.61) 1.35 (1.01 ; 1.80) 1.47 (1.08 ; 1.99)
 Q3 (57.9–78.9 cm3) 136/60,359 1.48 (1.13 ; 1.93) 1.77 (1.33 ; 2.35) 1.92 (1.42 ; 2.60)
 Q4 (>78.9 cm3) 183/61,065 2.08 (1.61 ; 2.68) 2.60 (1.96 ; 3.45) 2.71 (2.01 ; 3.67)
P trend   <0.001 <0.001 <0.001
Dense volume (per SD increase)# 523/238,696 1.34 (1.23 ; 1.46) 1.45 (1.32 ; 1.60) 1.45 (1.32 ; 1.60)
  1. HR 1 Cox proportional hazards analysis where age was used as the underlying time scale, HR 2 dense volume HR’s are adjusted for nondense volume (quartiles), HR invasive Cox proportional hazards analysis with only invasive breast cancers, where age was used as the underlying time scale. Dense volume HRs were adjusted for nondense volume (quartiles), NA Not applicable
  2. P trend was determined by adding the categorical measures as a continuous measure into the model
  3. #Continuous measures were natural-logarithm-transformed to establish normal distributions