Table 1 Baseline characteristics of the entire study population

Age (years)^*

43.5 (8.7)

43.5 (8.7)

46.6 (9.2)

Menopausal status

 Premenopausal

72,620 (80.8)

72,512 (80.8)

108 (75.5)

 Postmenopausal

16,953 (18.9)

16,920 (18.9)

33 (23.1)

 Missing

282 (0.3)

280 (0.3)

2 (1.4)

Body mass index category

 Underweight

6,603 (7.4)

6,596 (7.4)

7 (4.9)

 Normal

51,990 (57.9)

51,913 (57.9)

77 (53.9)

 Overweight

15,763 (17.5)

15,742 (17.6)

21 (14.7)

 Obese

15,395 (17.1)

15,358 (17.1)

37 (25.9)

 Missing

104 (0.1)

103 (0.1)

1 (0.7)

Education level

 < College graduate

26,018 (29.0)

25,972 (29.0)

46 (32.2)

 ≥ College graduate

58,191 (64.8)

58,105 (64.8)

86 (60.1)

 Unknown

5,646 (6.3)

5,635 (6.3)

11 (7.7)

First-degree family history of breast cancer

 Yes

2,410 (2.7)

2,407 (2.7)

3 (2.1)

 No

87,171 (97.0)

87,032 (97.0)

139 (97.2)

 Unknown

274 (0.3)

273 (0.3)

1 (0.7)

History of benign breast disease^†

 Yes

7,885 (8.8)

7,867 (8.8)

18 (12.6)

 No

74,141 (82.5)

74,029 (82.5)

112 (78.3)

 Unknown

7,829 (8.7)

7,816 (8.7)

13 (9.1)

Five-year risk based on Gail model (%)

 < 0.83%

88,972 (99.0)

88,831 (99.0)

141 (98.6)

 0.83–1.66%

593 (0.7)

593 (0.7)

0 (0)

 ≥ 1.67%

5 (0.0)

5 (0.0)

0 (0)

 Unknown

285 (0.3)

283 (0.3)

2 (1.4)

Equipment (%)

 Senographe, GE

87,686 (97.6)

87,545 (97.6)

141 (98.6)

 Selenia, Hologic

2,169 (2.4)

2,167 (2.4)

2 (1.4)

Mammography density

 A. Almost entirely fatty

1,035 (1.2)

1,033 (1.2)

2 (1.4)

 B. Scattered fibroglandular tissue

10,528 (11.7)

10,512 (11.7)

16 11.2)

 C. Heterogeneously dense

40,943 (45.6)

40,877 (45.6)

66 (46.2)

 D. Extremely dense

37,349 (41.6)

37,290 (41.6)

59 (41.3)

AI-driven mammographic density

 A. Almost entirely fatty

501 (0.6)

500 (0.6)

1 (0.7)

 B. Scattered fibroglandular tissue

16,771 (18.7)

16,748 (18.7)

23 16.1)

 C. Heterogeneously dense

55,947 (62.3)

55,856 (62.3)

91 63.6)

 D. Extremely dense

16,636 (18.5)

16,608 (18.5)

28 (19.6)