Table 2 Characteristics of mammographically occult breast cancers according to the AI analysis

Total

40 (31.2)

88 (68.8)

Age^a

43.6 ± 9.8

50.9 ± 9.3

Malignancy score^a

53.6 ± 24.1

2.7 ± 6.2

Symptom

 Yes

19 (47.5)

16 (18.2)

 Palpable lump

19 (47.5)

10 (11.4)

 Bloody nipple discharge

0 (0)

6 (6.8)

Family history

 Yes

4 (10.0)

14 (15.9)

Breast density

 A

0 (0)

1 (1.1)

 B

1 (2.5)

5 (5.7)

 C

11 (27.5)

38 (43.2)

 D

28 (70.0)

44 (50.0)

Location (Laterality)

 Right

21 (52.5)

37 (42.0)

 Left

19 (47.5)

51 (58.0)

Location (Quadrant)

 UOQ

21 (52.5)

47 (53.4)

 UIQ

9 (22.5)

24 (27.3)

 LOQ

5 (12.5)

7 (8.0)

 LIQ

5 (12.5)

10 (11.4)

Ultrasonographic tumor size^a

17.0 ± 10.0

13.4 ± 14.6

 < 10 mm

8 (20.0)

43 (48.9)

 10–14 mm

13 (32.5)

28 (31.8)

 15–19 mm

6 (15.0)

9 (10.2)

 20–49 mm

12 (30.0)

3 (3.4)

 ≥ 50 mm

1 (2.5)

5 (5.7)

Detectability on MRI^b

 Yes

32 (97.0)

61 (96.8)

Histologic type

 Ductal carcinoma

34 (85.0)

79 (89.8)

 Lobular carcinoma

4 (10.0)

8 (9.1)

 Mucinous carcinoma

1 (2.5)

1 (1.1)

 Adenoid cystic carcinoma

1 (2.5)

0 (0)

Nuclear grade

 1

2 (5.0)

9 (10.2)

 2

31 (77.5)

67 (76.1)

 3

7 (17.5)

12 (13.6)

Histologic grade^b

 1

3 (8.1)

10 (14.9)

 2

27 (73.0)

48 (71.6)

 3

7 (18.9)

9 (13.4)

Molecular subtype^b

 Luminal A

21 (55.3)

54 (66.7)

 Luminal B

9 (23.7)

17 (21.0)

 HER-2

4 (10.5)

5 (6.2)

 Triple-negative

4 (10.5)

5 (6.2)

Neoadjuvant chemotherapy^b

 Yes

12 (32.4)

5 (6.2)

Operation method^b

 Mastectomy

21 (56.8)

18 (22.2)

 Breast-conserving operation

16 (43.2)

63 (77.8)

Invasiveness^b

 DCIS

3 (8.1)

20 (24.7)

 Invasive carcinoma

34 (91.9)

61 (75.3)

Histologic upgrade^b

 Yes

6 (16.2)

9 (11.1)

Invasive tumor size^a,b

12.7 ± 14.1

8.7 ± 9.5

 < 10 mm

15 (40.5)

47 (58.0)

 10–14 mm

9 (24.3)

18 (22.2)

 15–19 mm

5 (13.5)

6 (7.4)

 20–49 mm

7 (18.9)

10 (12.3)

 ≥ 50 mm

1 (2.7)

0 (0)

Axillary lymph node metastasis^b

 Yes

11 (29.7)

7 (8.6)