Table 2.
Association between mammographic measures and breast cancer risk
| 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) |
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
P trend was determined by adding the categorical measures as a continuous measure into the model
#Continuous measures were natural-logarithm-transformed to establish normal distributions