Table 2. Kaplan-Meier univariable analysis.

Variables	Median overall survival (months)	P value
Sex
Female	NA*	0.067
Male	35
Age (years)
≤60	63	0.479
>60	57
Smoking status
Never	63	0.367
Even or current	46
Smoking index
≤800	63	0.002
>800	20
Tumor location
Peripheral	63	0.231
Central	20
Neoadjuvant therapy
No	63	0.36
Yes	31
Surgical resection method
Pulmonary lobectomy	63	0.124
Other pneumoresection	27
Histological subtype
P-SCLC	46	0.375
C-SCLC	NA*
Pathological TNM stage		0.01
Stage I vs. stage II	NA	0.003
Stage I vs. stage III	20	0.019
Stage II vs. stage III	46	0.332
Postoperative chemotherapy
≤4 courses	35	0.003
>4 courses	NA*
Postoperative radiotherapy
No	57	0.886
Yes	NA*

NA*, cumulative survival rate was greater than 50% across the entire survival curve. C-SCLC, mixed histology small cell lung cancer; P-SCLC, pure small cell lung cancer.