Table 2 Mammographic breast density and risk estimates for breast DCIS and invasive breast cancer
Exposure variable | Invasive breast cancer (n) | Breast DCIS (n) | Controls (n) | Invasive versus controls | DCIS versus controls | DCIS versus invasive |
|---|---|---|---|---|---|---|
Mean percentage density (%) | ||||||
<10 | 63 | 18 | 158 | 1 (reference) | 1 (reference) | 1 (reference) |
10–24.9 | 110 | 23 | 170 | 1.81 (1.21–2.70) | 1.15 (0.57–2.30) | 0.65 (0.31–1.35) |
25–49.9 | 174 | 34 | 212 | 2.53 (1.69–3.78) | 1.29 (0.64–2.59) | 0.56 (0.27–1.17) |
≥50 | 135 | 44 | 127 | 3.58 (2.26–5.66) | 2.86 (1.38–5.94) | 0.89 (0.41–1.91) |
P value for trend | <0.0001 | 0.0010 | ||||
Mean breast dense area (cm2) | ||||||
<15 | 95 | 26 | 209 | 1 (reference) | 1 (reference) | 1 (reference) |
15–29.9 | 136 | 29 | 200 | 1.58 (1.12–2.23) | 1.05 (0.58–1.92) | 0.75 (0.40–1.40) |
30–44.9 | 109 | 28 | 133 | 1.93 (1.32–2.81) | 1.70 (0.90–3.22) | 0.92 (0.48–1.76) |
≥45 | 142 | 36 | 125 | 2.92 (2.01–4.25) | 2.59 (1.39–4.82) | 0.99 (0.53–1.86) |
P value for trend | <0.0001 | 0.0026 | ||||