Table 2 Mammographic features in tumor and nontumor side in cases and control subjects

Percentage mammographic density on tumor side, median (IQR)

23.0 (6.1–44.1)

12.2 (2.4–32.8)

4.0 × 10⁻¹⁰

Percentage mammographic density on nontumor side, median (IQR)

21.7 (5.1–43.4)

12.5 (2.7–33.2)

2.5 × 10⁻⁷

Tumor vs. nontumor side, percentage mammographic density

1.1 (7.8)

–

3.4 × 10⁻³

Number of microcalcifications on tumor side, mean (SD)

6.1 (15.3)

2.6 (13.1)

4.0 × 10⁻²⁰

Number of microcalcifications on nontumor side, mean (SD)

3.4 (13.0)

2.6 (12.2)

0.03

Tumor vs. nontumor side, microcalcifications

2.7 (17.9)

–

1.9 × 10⁻³

Number of masses on tumor side, mean (SD)

0.77 (0.92)

0.56 (0.76)

8.4 × 10⁻⁶

Number of masses on nontumor side, mean (SD)

0.51 (0.75)

0.55 (0.78)

0.39

Tumor vs. nontumor side, masses

0.26 (1.1)

–

9.2 × 10⁻³

 Percentage mammographic density, mean (SD)

3.8 (4.0)

3.1 (3.7)

1.7 × 10⁻⁶

 Microcalcifications, mean (SD)

2.9 (6.1)

1.6 (5.7)

4.0 × 10⁻¹⁶

 Number of masses, mean (SD)

0.33 (0.42)

0.28 (0.40)

0.02