Table 4. Results of Cox regression analyses for independent prognostic factors for overall survival (OS) after brain metastasis (BM).

	Univariate analysis		Multivariate analysis
Factor	Crude HR (95% CI)	P a	Adjusted HR (95% CI)	P a
Menopausal status (pre- vs post-menopausal)	0.59 (0.43–0.81)	0.003	NS	NS
Age at BMb (years) (1 year increase in age)	1.03 (1.01–1.04)	<0.001	1.02 (1.01–1.03)	0.003
Number of brain metastases lesions (multiple vs solitary)	1.50 (1.03–2.19)	0.035	1.84 (1.25–2.72)	0.002
Leptomeningeal seedingc (yes vs no)	1.78 (1.15–2.74)	0.010	NS	NS
Chemotherapy after BM (yes vs no)	0.24 (0.18–0.33)	<0.001	0.27 (0.19–0.39)	<0.001
Hormonal therapy after BM (yes vs no)	0.56 (0.34–0.93)	0.025	0.44 (0.26–0.73)	0.001
Anti-HER2 treatment after BM (yes vs no)	0.41 (0.30–0.56)	<0.001	0.62 (0.43–0.89)	0.009

Abbreviations: HR=hazard ratio; CI=confidence interval; NS=not significant; BM=brain metastasis; OS=overall survival.

Note: The following factors were not significantly associated with OS after BM in univariate analysis: medical centre type, stage or nuclear grade of primary breast tumour at diagnosis, oestrogen and progesterone receptor status of primary breast tumour at diagnosis, duration between diagnosis of breast cancer and first metastases, brain as site of first metastasis, chemotherapy before diagnosis of BM, anti-HER2 treatment before diagnosis of BM, and hormonal therapy before diagnosis of BM.

^aP-value from the proportional hazards model.

^bVariable modelled as a continuous variable.

^cPatients with missing or unknown value(s) for this variable were excluded.