Table 1. Characteristics of the included studies in this meta-analysis.

Author, year	Patients	Comparisons	Number	Age, median [range], years	Follow-up (months)	Study design	Quality assessment
Ya-Nan Wang, et al., 2018	pTNM stage I-IIIB	4LD- group	518	58 [25–80]	71.6	Cohort study with historic controls	NOS: 8
		4LD+ group	139		39.4
Likui Fang, et al., 2019	pTNM stage I-IIIB	4LD- group	357	62 [32–81]		Cohort study with historic controls	NOS: 7
		4LD+ group	48		21
Kejia Zhao, et al., 2019	pTNM stage I-IIIA	4LD- group	460	–		Cohort study with historic controls	NOS: 6
		4LD+ group	460		40
Shang-Qi Song, et al., 2015	pTNM stage I-IV	4LD- group	383	60 [22–83]		Cohort study with historic controls	NOS: 6
		4LD+ group	260		–