Table 1.

The characteristics of included studies.

Author(s)	YOP	Patients			Cancer	Studied protein	Metastasis	Analysis for HRs	Quality score
		MA	FE	T
Pinheiro et al.32	2010	0	249	249	BC	MCT4	LNM	N/A	8
Nakayama et al.19	2012	59	46	105	CRC	MCT4	LNM, DM	M	8
Choi et al.33	2014	311	49	360	UCB	MCT1, 4	LNM, DM	M	8
Eilertsen et al.28	2014	253	82	335	NSCLC	MCT4	None	M	8
Gao et al.22	2014	281	37	318	HCC	MCT1	DM	M	6
Ohno et al.23	2014	168	57	225	HCC	MCT4	DM	M	7
Polanski et al.31	2014	N/A	N/A	78	SCLC	MCT1	None	M	7
Yan et al.26	2014	85	58	143	GC	MCT1, 4	None	M	8
Zhu et al.34	2014	59	40	99	OSCC	MCT4	LNM, DM	M	7
Kim et al.35	2015	127	53	180	ccRCC	MCT1	DM	M	6
Pinheiro et al.30	2015	10	66	76	ACC	MCT1, 4	None	U	6
Curry et al.29	2016	14	32	46	TC	MCT4	LNM	N/A	6
Martins et al.18	2016	308	179	487	CRC	MCT4	DM	M	7
Petrides et al.21	2016	65	42	107	CRC	MCT4	None	M	7
Shang et al.36	2016	24	56	80	GBC	MCT1, 4	LNM, DM	M	7
Johnson et al.25	2017	0	257	257	BC	MCT1, 4	None	M	8
Latif et al.37	2017	0	90	90	EC	MCT1	LNM	M	8
Ruan et al.27	2017	80	66	146	LAC	MCT4	LNM, DM	M	8
Abe et al.20	2018	131	106	237	CRC	MCT1, 4	LNM, DM	N/A	8
Chen et al.24	2018	182	31	213	HCC*	MCT4	DM	U	6

*Indicates performing analysis after hepatectomy. ACC, adrenocortical carcinoma; BC, breast cancer; ccRCC, clear cell renal cell carcinoma; CRC, colorectal cancer; DM, distant metastasis; EC, endometrial cancer; FE, female; GBC, gallbladder cancer; GC, gastric cancer; HCC, hepatocellular carcinoma; LAC, lung adenocarcinoma; LMN, lymph node metastasis; M, multivariate; MA, male; MCT, monocarboxylate transporter; N/A, not available; NSCLC, non-small-cell lung cancer; OSCC, oral squamous cell carcinoma; SCLC, small-cell lung cancer; T, total; TC, thyroid cancer; U, univariate; UCB, urothelial carcinoma of the bladder; YOP, year of publication.