Table 3. Factors independently predicting PFS and OS.

Cox regression results of PFS (n = 364)
Independent predictive factors	Hazard ratio (HR)	95% CI	P value
ECOG
0	Ref
1–2	1.53	1.12 – 2.09	0.008
Number of metastatic organ sites
1	Ref
2	1.21	0.89 – 1.65	0.224
≥3	1.78	1.30 – 2.44	<0.001
Time between breast surgery and recurrent disease
<12 months	Ref
≥12 months	0.58	0.44 – 0.75	<0.001
PBCT used as first-line chemotherapy
No	Ref
Yes	0.63	0.47 – 0.84	0.002
Cox regression results of PFS in subgroup of PBCT as the first line chemotherapy (n = 218)
ECOG
0	Ref
1–2	1.52	1.06 – 2.18	0.022
Number of metastatic organ sites
1	Ref
2	1.47	1.01 – 2.13	0.045
≥3	2.23	1.53 – 3.25	<0.001
Time between breast surgery and recurrent disease
<12 months	Ref
≥12 months	0.63	0.46 – 0.86	0.004
Type of PBCT
Non-cisplatin-based	Ref
Cisplatin-based	0.59	0.35 – 0.99	0.046
Cox regression results of OS (n = 379)
Number of metastatic organ sites
1	Ref
2	1.32	0.94 – 1.86	0.108
≥ 3	2.67	1.92 – 3.71	<0.001
Time between breast surgery and recurrent disease
< 12 months	Ref
≥ 12 months	0.43	0.32 – 0.57	<0.001
Total lines of PBCT received
< 2	Ref
≥ 2	0.73	0.56 – 0.94	0.016

Abbreviations: PBCT, platinum-based chemotherapy; PFS: progression-free survival; OS: overall survival; CI: confidence interval; Ref: reference category.