Table 5

RRa of breast cancer in relation to presence of class 1 and 2 calcifications, percent density, and Wolfe classification on prior screening mammograms

No calcificationClass 2Class 1
Percent density
 ≤26.71.0 (reference)2.3 (0.9–6.0)∞ (0.16–∞)
[19, 63][11, 11][1, 0]
 26.8–50.11.7 (1.1–2.7)3.0 (1.3–7.1)2.4 (0.6–10.0)
[34, 65][17, 12][7, 4]
 50.2–70.23.2 (2.1–5.0)6.1 (2.9–13.7)14.1 (3.6–93.3)
[65, 52][32, 12][13, 2]
 ≥70.34.3 (2.8–6.6)5.6 (3.0–10.8)10.9 (2.7–73.1)
[74, 49][51, 20][13, 2]
Wolfe classification
 N1 and P11.0 (reference)1.4 (0.6–3.3)0.9 (0.04–10.5)
[25, 73][11, 18][1, 2]
 P22.8 (1.9–4.0)5.4 (3.2–9.2)7.3 (3.0–20.7)
[143, 149][85, 32][28, 6]
 DY5.4 (2.9–10.3)6.5 (2.3–21.1)∞ (4.0–∞)
[24, 7][15, 5][5, 0]
  • a Adjusted for age, study, and other types of calcifications. Numbers in parentheses, 95% CI; numbers in brackets, number of cases and controls.