Table 1.

Characteristics of patients included in this study

Feature	Grouping	N or value	%
Age	Mean	53.9
	Range	38–81
Histologic type	Invasive ductal carcinoma	30	81.1
	Others	4	10.8
	Unknown	3	8.1
Histologic grade	1	1	2.7
	2	8	21.6
	3	20	54.1
	Unknown	8	21.6
TNM stage	1	6	16.2
	2	13	35.1
	3	9	24.3
	4	1	2.7
	Unknown	8	21.6
ER status of primary tumor	Positive	16	43.2
	Negative	21	56.8
PR status of primary tumor	Positive	13	35.1
	Negative	24	64.9
HER2 status of primary tumor	Positive	19	51.4
	Negative	18	48.6
Primary breast cancer subtype	HR+, HER2−	13	35.1
	HR+, HER2+	3	8.1
	HR−, HER2+	16	43.2
	HR−, HER2−	5	13.5
Multiplicity	Single brain metastasis	28	75.7
	Multiple metastasis	9	24.3
Brain metastasis location	Supratentorial	25	67.6
	Infratentorial	8	21.6
	Both	4	10.8

ER estrogen receptor, PR progesterone receptor, HER2 human epidermal growth factor receptor 2, HR hormone receptor