Table 1. Baseline characteristics of all patients.

Characteristic	Statistic result
Age, years
Median [range]	64 [24–87]
<65	198 (56.7%)
≥65	151 (43.3%)
Gender
Male	233 (66.8%)
Female	116 (33.2%)
Smoking
Never	106 (30.4%)
Current/former	243 (69.6%)
ECOG PS
0–1	275 (78.8%)
≥2	66 (18.9%)
Missing	8 (2.3%)
Pathology
SCLC	341 (97.7%)
Mixed-SCLC	8 (2.3%)
N-stage
N0	15 (4.3%)
N1	5 (1.4%)
N2	156 (44.7%)
N3	151 (43.3%)
Missing	22 (6.3%)
Liver metastases
Only liver	123 (35.2%)
Involved other organs	226 (64.8%)
Brain metastases
No	313 (89.7%)
Yes	36 (10.3%)
Bone metastases
No	201 (57.6%)
Yes	148 (42.4%)
Intrapulmonary metastasis
No	297 (85.1%)
Yes	52 (14.9%)
Malignant pleural effusion
No	302 (86.5%)
Yes	47 (13.5%)
Number of involved metastatic organs
<3	264 (75.6%)
≥3	85 (24.4%)
First-line systemic therapy	286 (81.9%)
Chemotherapy	263 (92.0%)
Chemotherapy + immunotherapy	14 (4.9%)
Chemotherapy + angiogenesis inhibitors	9 (3.1%)
Second-line systemic treatment	153 (43.8%)
Chemotherapy	131 (85.6%)
Chemotherapy + immunotherapy	5 (3.3%)
Chemotherapy + angiogenesis inhibitors	8 (5.2%)
Immunotherapy	1 (0.7%)
Angiogenesis inhibitors	4 (2.6%)
Immunotherapy + angiogenesis inhibitors	2 (1.3%)
Chemotherapy + immunotherapy + angiogenesis inhibitors	2 (1.3%)
Third-line or beyond treatment	81 (23.2%)
Chemotherapy	58 (71.6%)
Chemotherapy + immunotherapy	7 (8.6%)
Chemotherapy + angiogenesis inhibitors	11 (13.6%)
Angiogenesis inhibitors	5 (6.2%)
Thorax radiotherapy
No	330 (94.6%)
Yes	19 (5.4%)
Brain radiotherapy
No	302 (86.5%)
Yes	47 (13.5%)
Other radiotherapy
No	323 (92.6%)
Yes	26 (7.4%)
Treatment
No systemic treatment	60 (17.2%)
Systemic treatment	220 (63.0%)
Systemic treatment + local radiotherapy	69 (19.8%)

ECOG PS, Eastern Cooperative Oncology Group performance status; SCLC, small cell lung cancer.