Table 2. Clinicopathological features of included cases.

	Characteristics (number of individuals with available data)		n	%
All BC (HER2 IHC 0, 1+, 2+/ISH-, 2+/ISH+ and 3+)	Histology (n = 2,042)	Ductal carcinoma	1776	87.0
		Lobular carcinoma	136	6.7
		Other	130	6.4
	Lymphovascular invasion (n = 1,487)	Positive	547	36.8
		Negative	940	63,2
	KI-67 expression (n = 1,487)	High	283	19.0
		Low	1204	81.0
HER2-negative tumors (IHC 0, 1+ and 2+/ISH)	Histology (n = 1,542)	Ductal carcinoma	1340	86.9
		Lobular carcinoma	113	7.3
		Other	89	5.8
	Molecular subtypes (n = 1,186)	Luminal	751	63.3
		TNBC	435	36.7
	Clinical stage (n = 950)	I	59	6.2
		II	367	38.6
		III	524	55.2
	Grade (n = 1,366)	1	69	05.0
		2	605	44.3
		3	692	50.7
HER2-low tumors (IHC 1+ and 2+/ISH-)	Histology (n = 655)	Ductal carcinoma	594	90.7
		Lobular carcinoma	31	4.7
		Other	30	4.6
	Molecular subtypes (n = 491)	Luminal	367	74.7
		TNBC	124	25.2
	Clinical stage (n = 607)	I	32	5.3
		II	259	42.7
		III	316	52.1
	Grade (n = 629)	1	45	7.1
		2	299	47.5
		3	285	45.3
	Lymphovascular invasion (n = 333)	Positive	62	18.6
		Negative	271	81.4
	KI-67 expression (n = 366)	High	137	37.5
		Low	229	62.5

BC, breast cancer. IHC, immunohistochemistry. ISH, In situ hybridization. TNBC, triple negative breast cancer