Table 1 Clinical characteristics of the cohort

Characteristic

Cohort

Geographic origin

Japan

Type of cohot

Clinic-based

Centralized HER2 assessment

no

Centralized clinical data collection

no

Length of follow-up (months)

3.4-63.3

Total Number of patients

75

Parameter

Number of patients (%)

HER2 status by IHC

75 (100)

HER2 status by FISH

9(12.0)

Total

Log ₁₀ HER2 expression • Median

Log ₁₀ HER2 expression • Median

HER2 test at the local hospital

2+

20 (26.7)

11 (28.9)

9 (24.3)

3+

55 (73.3)

27 (71.1)

28 (75.7)

Centrally reviewed IHC

0

11 (14.7)

1 (2.6)

10 (27.0)

1+

14 (18.7)

2 (5.3)

12 (32.4)

2+

18 (24.0)

9 (23.7)

9 (24.3)

3+

32 (42.7)

26 (68.4)

6 (16.2)

HER2 score on repeat testing

Mean (s.d.)

148 (101)

210 (71)

84 (87)

Min - Max

0 - 290

0 - 290

0 - 290

Hormone receptor status

ER+ PR+

10 (13.3)

6 (15.8)

4 (10.8)

ER+ PR-

2 (2.7)

1 (2.6)

1 (2.7)

ER- PR+

3 (4.0)

0

3 (8.1)

ER- PR-

60 (80.0)

31 (81.6)

29 (78.4)

ER unknown, PR-

0

0

0

ER unknown, PR unknown

0

0

0

Nodal status

Negative

21 (28.0)

14 (36.8)

7 (18.9)

1 to 3 positive nodes

23 (30.7)

9 (23.7)

14 (37.8)

4 to 10 positive nodes

8 (10.7)

4 (10.5)

4 (10.8)

> 10 positive nodes

17 (22.0)

7 (18.4)

10 (27.0)

Status missing

6 (8.0)

4 (10.5)

2 (5.4)

Tumor size

< = 2 cm

9 (12.0)

5 (13.2)

4 (10.8)

>2 cm & < = 5 cm

37 (49.3)

19 (50.0)

18 (48.7)

>5 cm

17 (22.7)

6 (15.8)

11 (29.7)

Missing

12 (16.0)

8 (21.1)

4 (10.8)

Prior adjuvant therapy

Adj HT

30 (40.0)

15 (39.5)

15 (40.5)

Adj CT

51 (68.0)

23 (60.5)

28 (75.7)

Adj HT only

5 (6.7)

2 (5.3)

3 (8.1)

Adj CT only

26 (34.7)

10 (26.3)

16 (43.2)

Adj HT & Adj CT

25 (33.3)

13 (34.2)

12 (32.4)

neither HT nor CT

19 (25.3)

13 (34.2)

6 (16.2)

Number of pre-chemotherapy before trastuzumab treatment*

0

41 (54.7)

18 (47.4)

23 (62.2)

1

15 (20.0)

9 (23.7)

6 (16.2)

2 or 3

7 (9.3)

3 (7.9)

4 (10.8)

N.A.

12 (16.0)

8 (21.1)

4 (10.8)

Tumor stage

Recurrence

66 (88.0)

32 (84.2)

34 (91.9)

Advanced

9 (12.0)

6 (15.8)

3 (8.1)

Number of met sites

1 or 2

49 (65.3)

25 (65.8)

24 (64.9)

3 or 4

25 (33.3)

12 (31.6)

13 (35.1)

unknown

1 (1.3)

1 (2.6)

0

Brain mets

yes

7 (9.3)

5 (13.2)

2 (5.4)

no

68 (90.7)

33 (86.8)

35 (94.6)

Treatment

Herceptin + chemo

63 (84.0)

31 (81.6)

32 (86.5)

Herceptin only

12 (16.0)

7 (13.5)

5 (18.4)