Table 3. Summary of the subgroup analysis.

Subgroups	Studies (n)	Patients (n)	Effects model	HR (95% CI)	P	Heterogeneity
						I2 (%)	P
OS
Total	10	935	FEM	2.70 (1.97–3.71)	<0.001	0	0.461
Geographical region
Asia	8	723	FEM	2.89 (2.05–4.08)	<0.001	0	0.713
Non-Asia	2	212	REM	2.16 (0.48–9.66)	0.314	69.1	0.072
TNM stage
I–IV	8	775	FEM	2.76 (1.97–3.86)	<0.001	0	0.518
II–IV	2	160	REM	2.34 (0.54–10.13)	0.256	59.2	0.117
Treatment
Radiotherapy	2	54	FEM	1.90 (1.00–3.61)	0.049	0	0.358
Chemoradiotherapy	4	589	FEM	3.79 (2.28–6.29)	<0.001	0	0.925
Mixed	4	292	FEM	2.39 (1.41–4.03)	0.001	31.5	0.223
Sample size
<100	7	342	FEM	2.45 (1.63–3.67)	<0.001	20.7	0.272
≥100	3	593	FEM	3.16 (1.90–5.24)	<0.001	0	0.739
Cutoff value
≥5%	2	212	REM	2.16 (0.48–9.66)	0.314	69.1	0.072
≥10%	3	427	FEM	2.79 (1.75–4.47)	<0.001	0	0.747
≥50%	3	192	FEM	2.52 (1.38–4.59)	0.003	14.8	0.309
Others	2	104	FEM	4.72 (1.82–12.23)	0.001	0	0.533
Analysis of HR
Univariate	6	620	FEM	2.74 (1.89–3.97)	<0.001	0	0.646
Multivariate	4	315	FEM	2.61 (1.41–4.82)	0.002	44.2	0.146
Study design
Retrospective	9	794	FEM	2.61 (1.88–3.61)	<0.001	0	0.443
Prospective	1	141	-	4.96 (1.31–18.81)	0.019	-	-
DFS
Total	7	881	FEM	1.93 (1.49–2.50)	<0.001	25.3	0.236
Geographical region
Asia	5	669	FEM	1.91 (1.45–2.53)	<0.001	1.5	0.398
Non-Asia	2	212	REM	2.48 (0.55–11.19)	0.237	74.7	0.047
TNM stage
I–IV	5	632	FEM	1.78 (1.33–2.39)	<0.001	16.2	0.312
II–IV/III–IV	2	249	FEM	2.59 (1.46–4.60)	0.001	49.2	0.161
Treatment
Chemoradiotherapy	2	475	REM	2.72 (0.87–8.50)	0.085	68.1	0.077
Mixed	5	406	FEM	1.89 (1.36–2.64)	<0.001	17.9	0.300
Sample size
<100	3	174	FEM	2.26 (1.23–4.17)	0.009	49.5	0.138
≥100	4	707	FEM	1.86 (1.40–2.47)	<0.001	20.0	0.290
Cutoff value
≥5%	2	212	REM	2.48 (0.55–11.19)	0.237	74.7	0.047
≥10%	3	500	FEM	1.97 (1.40–2.79)	<0.001	0	0.433
Others	2	169	REM	2.31 (0.81-6.58)	0.118	56.4	0.130
Analysis of HR
Univariate	2	458	FEM	1.67 (1.20–2.32)	0.002	0	0.787
Multivariate	5	423	FEM	2.43 (1.60–3.69)	<0.001	33.6	0.197
Study design
Retrospective	6	740	FEM	1.83 (1.41–2.39)	<0.001	0	0.419
Prospective	1	141	-	5.76 (1.64–20.21)	0.006	-	-
DMFS
Total	3	605	REM	1.37 (0.78–2.38)	0.270	67.4	0.047
LRFS
Total	2	458	FEM	1.86 (1.11–3.12)	0.019	43.5	0.183