TABLE 2.

Subgroup analyses of the association between STAS and RFS

		Test of association			Test of heterogeneity		Egger's test		Begg's test
Variable	Studies	HR	95%CI	p value	I 2	p value	t (Bias)	p value	z	p value
Total	16	2.33	1.90–2.85	<0.001	50.0%	0.008	2.77	0.014	3.11	0.002
Treatment
Limited resection	6	3.58	2.40–5.34	<0.001	41.4%	0.115	1.36	0.233	0.6	0.548
Lobectomy	4	1.6	1.16–2.22	0.019	32.5%	0.218	2.33	0.145	1.02	0.308
AJCC TNM
7th	5	2.43	1.58–3.72	<0.001	42.9%	0.119	1.48	0.334	1.13	0.260
8th	11	2.32	1.81–2.96	<0.001	55.5%	0.01	1.43	0.039	2.81	0.005
Research region
Korea	3	4.86	2.43–9.74	<0.001	0.0%	0.49	1.5	0.394	0.00	1.000
China	4	1.88	1.61–2.19	<0.001	8.9%	0.356	0.33	0.766	−0.24	1.000
America	2	2.24	1.39–3.59	0.001	0.0%	0.679	–	–	0.00	1.000
Japan	6	2.82	1.64–4.86	<0.001	67.2%	0.006	0.96	0.382	0.60	0.548
Hungary	1	2.29	1.25–4.18	0.007	–	–	–	–	–	–
Sample size
≤400	7	2.25	1.64–3.09	<0.001	39.5%	0.116	2.82	0.024	2.60	0.009
>400	9	2.43	1.82–3.25	<0.001	59.6%	0.008	1.34	0.085	1.79	0.074

Abbreviations: AJCC, American Joint Committee on Cancer; RFS, recurrence‐free survival; STAS, spread through air space; TNM, tumor, node, metastasis.