Table 4 Multivariate Cox regression results of mortality risk on various clinical variables

Brain metastasis

 No

ref

0.246

 Yes

1.42 (0.78–2.58)

Liver metastasis

 No

ref

< 0.001

 Yes

2.49 (1.50–4.14)

Extrathoracic lymph node metastasis

 No

ref

0.634

 Yes

1.11 (0.72–1.70)

1. Line treatment

< 0.001

 Cisplatin+etoposide

ref

 Carboplatin+etoposide

2.20 (1.18–4.08)

0.012

 Oral etoposide

6.46 (1.29–32.14)

0.023

 Carboplatin+etoposide+atezolizumab

0.36 (0.16–0.81)

0.013

2. Line treatment

0.020

 Topotecan

ref

 Cisplatin+irinotecan

0.62 (0.31–1.26)

0.193

 Cisplatin+etoposide

0.33 (0.15–0.71)

0.004

 CAV

1.30 (0.59–2.82)

0.508

 Other

0.96 (0.58–1.60)

0.904

Number of cycles in the first line

 ≤ 4

ref

0.933

 > 4

0.98 (0.61–1.56)

PCI

 No

ref

0.045

 Yes

0.60 (0.36–0.98)