Table 2. Prognostic value of glycolysis markers in HNSCC patients.

	Variable	Study NO.	Sample size	HR [95% CI]	P value	Heterogeneity
						I2 (%)	P value
OS	Overall	21	1893	2.12 [1.79, 2.50]	<0.001	0	0.45
	Ethnicity
	Asian	12	1039	2.53 [1.93, 3.30]	<0.001	0	0.80
	Caucasian	9	854	1.89 [1.52, 2.34]	<0.001	22	0.24
	Glycolysis marker
	GLUT1	12	998	1.94 [1.57, 2.39]	<0.001	2	0.42
	MCT4	1	99	3.64 [1.60, 8.29]	0.002	-	-
	HK2	3	324	2.05 [1.29, 3.26]	0.002	0	0.96
	PKM2	3	311	2.92 [1.85, 4.59]	<0.001	0	0.41
	GLUT4	2	161	1.93 [0.97, 3.81]	0.06	61	0.11
	Tumor location
	OSCC	11	982	2.71 [2.12, 3.46]	<0.001	0	0.60
	NPC	3	250	1.85 [1.17, 2.91]	0.008	0	0.93
	LSCC	2	106	3.04 [0.78, 11.80]	0.11	0	0.73
	Oropharyngeal SCC	1	274	1.50 [1.05, 2.15]	0.026	-	-
	Sample size
	Large	10	1321	2.06 [1.69, 2.50]	<0.001	0	0.50
	Small	11	566	2.29 [1.66, 3.17]	<0.001	13	0.32
DFS	Overall	9	771	1.76 [1.06, 2.93]	0.03	56	0.02
	Ethnicity
	Asian	4	303	2.24 [1.42, 3.54]	<0.001	0	0.52
	Caucasian	5	468	1.46 [0.61, 3.49]	0.39	70	0.01
	Glycolysis marker
	GLUT1	4	351	1.55 [0.92, 2.64]	0.10	1	0.39
	MCT4	2	141	4.55 [2.24, 9.23]	<0.001	44	0.18
	HK2	1	97	1.01 [0.50, 2.05]	0.98	-	-
	PKM2	1	111	2.53 [1.01, 6.37]	0.008	-	-
	GLUT4	1	71	0.78 [0.32, 1.92]	0.59	-	-
	Tumor location
	OSCC	6	506	2.33 [1.18, 4.60]	0.01	52	0.06
	Sample size
	Large	5	565	1.75 [0.94, 3.27]	0.08	53	0.07
	Small	4	206	1.88 [0.68, 5.18]	0.22	68	0.02