TABLE 3.

Results of subgroup analysis.

Sub-group	Number of effects	Heterogeneity	Subgroup analysis
		I 2 (%)	HR	95% CI	p value
OS
Age
≥65 years old	6	51	0.88	0.69–1.13	0.33
<65 years old	5	0	0.67	0.49–0.92	0.01
Region
Asian	4	33	0.69	0.47–1.00	0.05
North America and Europe	7	38	0.90	0.78–1.04	0.16
Quality of studies
NOS>7.18	5	34	0.66	0.49–0.88	0.005
NOS<7.18	6	4	0.94	0.81–1.09	0.42
Adjusted for comorbidity
Yes	4	7	0.97	0.82–1.13	0.66
No	7	8	0.66	0.51–0.85	0.002
Adjusted smoking
Yes	6	49	0.79	0.61–1.02	0.07
No	5	26	0.90	0.77–1.06	0.2
DFS
Age
≥65 years old	3	67	0.67	0.19–2.32	0.52
<65 years old	3	68	0.64	0.36–1.13	0.13
Region
Asian	4	67	0.55	0.27–1.12	0.1
North America and Europe	2	43	0.90	0.49–1.65	0.73
Quality of studies
NOS>7.18	2	20	0.49	0.26–0.92	0.03
NOS<7.18	2	81	0.73	0.55–0.97	0.03
Adjusted for comorbidity
Yes	3	81	0.78	0.40–1.51	0.46
No	3	20	0.48	0.22–1.03	0.06
Adjusted smoking
Yes	5	64	0.59	0.32–1.06	0.08
No	1	—	1.02	0.60–1.73	0.94
DSS
Age
≥65 years old	3	75	0.76	0.43–1.34	0.34
<65 years old	1	—	0.45	0.20–1.01	0.05
Region
Asia	1	—	0.45	0.20–1.01	0.05
North America and Europe	3	75	0.76	0.43–1.34	0.34
Quality of studies
NOS>7.18	2	0	0.38	0.22–0.65	0.0004
NOS<7.18	2	0	1.02	0.76–1.35	0.92
Adjusted for comorbidity
Yes	2	0	1.02	0.76–1.35	0.92
No	2	0	0.38	0.22–0.65	0.0004
Adjusted smoking
Yes	2	68	0.73	0.33–1.65	0.45
No	2	86	0.6	0.20–1.78	0.36

Abbreviations: OS, overall survival; DFS, disease-free survival; DSS, disease-specific survival; NOS, Newcastle-Ottawa Scale.