Table 3.

Subgroup analysis of the postoperative treatment outcomes

Subgroup	Category	Included studies	Sample size		Test for overall effect
			CRTS	SA	RR (95% CI)	P
Postoperative mortality based on ethnicity	The West	5	377	417	0.83 [0.47, 1.46]	0.52
	The East	2	115	128	0.56 [0.42, 0.75]	<0.0001
Postoperative complication based on ethnicity	The West	4	209	231	1.00 [0.87, 1.15]	0.98
	The East	5	357	387	1.23 [0.96, 1.56]	0.10
Local recurrence based on ethnicity	The West	4	283	279	0.51 [0.34, 0.76]	0.001
	The East	4	201	202	0.52 [0.33, 0.84]	0.008
Postoperative metastasis based on ethnicity	The West	4	283	279	0.93 [0.75, 1.16]	0.53
	The East	4	201	202	0.62 [0.44, 0.88]	0.007
Postoperative mortality based on histology	SCC	7	231	247	0.54 [0.42, 0.68]	<0.0001
	AC	5	295	313	1.26 [0.76, 2.06]	0.37

SCC: squamous cell carcinoma AC: adenocarcinoma.