Table 1.

Demographic and Clinical Characteristics of HER2-Positive MBC Patients.

Characteristics	Overall N (%)	Train N (%)	Test N (%)	P
Race
Black	41 (17.1)	28 (19.4)	13 (13.5)	0.136
Other	14 (5.8)	11 (7.6)	3 (3.1)
White	185 (77.1)	105 (72.9)	80 (83.3)
Age
<65	117 (48.8)	64 (44.4)	53 (55.2)	0.102
≥65	123 (51.2)	80 (55.6)	43 (44.8)
Marital status
Married	160 (66.7)	95 (66.0)	65 (67.7)	0.78
Unmarried	80 (33.3)	49 (34.0)	31 (32.3)
Grade
I	3 (1.2)	2 (1.4)	1 (1.0)	0.751
II	109 (45.4)	62 (43.1)	47 (49.0)
III	128 (53.3)	80 (55.6)	48 (50.0)
Laterality
Left	130 (54.2)	68 (47.2)	62 (64.6)	0.008
Right	110 (45.8)	76 (52.8)	34 (35.4)
T stage
T1	84 (35.0)	53 (36.8)	31 (32.3)	0.617
T2	120 (50.0)	67 (46.5)	53 (55.2)
T3	9 (3.8)	6 (4.2)	3 (3.1)
T4	27 (11.2)	18 (12.5)	9 (9.4)
N stage
N0	113 (47.1)	76 (52.8)	37 (38.5)	0.023
N1	89 (37.1)	46 (31.9)	43 (44.8)
N2	21 (8.8)	9 (6.2)	12 (12.5)
N3	17 (7.1)	13 (9.0)	4 (4.2)
M stage
M0	218 (90.8)	130 (90.3)	88 (91.7)	0.715
M1	22 (9.02)	14 (9.7)	8 (8.3)
Tumor size
<50	223 (92.9)	133 (92.4)	90 (93.8)	0.681
≥50	17 (7.1)	11 (7.6)	6 (6.2)
ER
Negative	15 (6.2)	11 (7.6)	4 (4.2)	0.276
Positive	225 (93.8)	133 (92.4)	92 (95.8)
PR
Negative	39 (16.2)	24 (16.7)	15 (15.6)	0.83
Positive	201 (83.8)	120 (83.3)	81 (84.4)
Surgery
No	22 (9.2)	15 (10.4)	7 (7.3)	0.411
Yes	218 (90.8)	129 (89.6)	89 (92.7)
Radiation
None/Unknown	176 (73.3)	108 (75.0)	68 (70.8)	0.475
Yes	64 (26.7)	36 (25.0)	28 (29.2)
Chemotherapy
No/Unknown	78 (32.5)	46 (31.9)	32 (33.3)	0.822
Yes	162 (67.5)	98 (68.1)	64 (66.7)