Abnormally expressed circular RNAs as novel non-invasive biomarkers for hepatocellular carcinoma: A meta-analysis

Table 1 Characteristics of the included studies for diagnosis and clinicopathologic features

Study	Ethnicity	Patient size	Control size	Control source	Sample type	CircRNA Name	Expression status	Method	Cut-Off value	Control gene	AUC	QUADAS score
Fu et al[12], 2017	Chinese	107	107	CH & LC	Tissue	hsa_circ_0003570	Decreased	qRT-PCR	12.24	GAPDH	0.70	4
Yao et al[25], 2017	Chinese	102	102	Adjacent non-cancerous liver tissue	Tissue	circZKSCAN1	Decreased	qRT-PCR	Unclear	GAPDH	0.834	4
Shang et al[21], 2016	Chinese	30	30	Adjacent nontumorous tissue	Tissue	hsa_circ_0005075	Increased	qRT-PCR	0.000586	GAPDH	0.94	6
Qin et al[20], 2016	Chinese	89	89	Paired adjacent liver tissues	Tissue	Hsa_circ_0001649	Decreased	qRT-PCR	0.00079	β-actin	0.63	6
Chen et al[11], 2018	Chinese	30	30	Para-tumorous tissues	Tissue	hsa_circ_0091582	Increased	qRT-PCR	Unclear	GAPDH	0.679	5
Chen et al[11], 2018	Chinese	30	30	Para-tumorous tissues	Tissue	hsa_circ_0128298	Increased	qRT-PCR	Unclear	GAPDH	0.664	5
Chen et al[11], 2018	Chinese	48	48	Para-tumorous tissues	Tissue	hsa_circ_0128298	Increased	qRT-PCR	Unclear	GAPDH	0.668	5
Huang et al[17], 2017	Chinese	102	129	Para-tumorous and CH tissues	Tissue	hsa_circ_0004018	Decreased	qRT-PCR	0.531	GAPDH	0.848	5
Zhang et al[28],2018	Chinese	104	52	Healthy control	Plasma	hsa_circ_0001445	Decreased	qRT-PCR	Unclear	GAPDH	0.862	5
Zhang et al[29], 2018	Chinese	104	57	LC	Plasma	hsa_circ_0001445	Decreased	qRT-PCR	Unclear	GAPDH	0.672	5
Zhang et al[29], 2018	Chinese	104	44	CH	Plasma	hsa_circ_0001445	Decreased	qRT-PCR	Unclear	GAPDH	0.764	5
Han et al[16], 2017	Chinese	80	80	Non-cancer tissue	Tissue	CircRNA pattern	/	qRT-PCR	Unclear	Unclear	0.988	3
Han et al[16], 2017	Chinese	20	20	Non-cancer tissue	Tissue	CircRNA pattern	/	qRT-PCR	Unclear	Unclear	0.976	3

AUC: Area under the curve; circRNA: Circular RNA; CH: Chronic hepatitis; LC: Liver cirrhosis; qRT-PCR: Quantitative real-time PCR; GAPDH: Reduced glyceraldehyde-phosphate dehydrogenase; QUADAS: Quality Assessment for Studies of Diagnostic Accuracy.

Table 2 Characteristics of the included studies for prognosis and clinicopathologic features

Study	Locale	Patient size	TNM stage (I/II/III/IV)	Sample type	CircRNA signature	Expression status	Survival indicator	Follow-up time	HR and 95%CI extraction	P-value (survival)	NOS scores
Cai et al[10], 2018	China	78	Unclear	Tissue	hsa_circ_0103809	Increased	OS	Unclear	Indirectly	0.001	6
Zhong et al[30], 2018	China	47	7, 15, 16, 9	Tissue	circC3P1	Decreased	OS	Unclear	Indirectly	0.030	6
Li et al[18], 2018	China	51	I–II: 24, III–IV: 27	Tissue	circRNA101368	Increased	OS	Unclear	Directly	0.001, 0.033	7
Weng et al[22], 2018	China	120	I–III: 60, 14, 46	Tissue	hsa_circ_0064428	Increased	OS	Unclear	Indirectly	0.033	7
Chen et al[11], 2018	China	78	Unclear	Tissue	hsa_circ_0128298	Increased	OS	Median: 37 months	Directly	0.009, 0.014	8
Gong et al[14], 2018	China	64	12, 22, 17, 13	Tissue	circ-ZEB1.33	Increased	OS	Unclear	Indirectly	0.015, 0.019	7
Yu et al[26], 2018	China	208	I: 62, II–III: 101	Tissue	cSMARCA5	Decreased	OS	Unclear	Directly	0.001, 0.021	7
Huang et al[17], 2017	China	80	I–II: 43, III–IV: 37	Tissue	hsa_circRNA_100338	Increased	OS	5 years	Indirectly	<0.01	8
Han et al[16], 2017	China	116	Unclear	Tissue	circMTO1	Decreased	OS	Unclear	Indirectly	0.0023	7
Guo et al[15], 2017	China	1800	Unclear	Tissue	circ-ITCH	Decreased	OS	Unclear	Directly	<0.001	6
Zhang et al[27], 2018	China	77	I–II: 34, III–IV: 43	Tissue	hsa_circ_0001649	Decreased	OS	Unclear	Directly	0.015, 0.011	6
Xu et al[23], 2018	China	76	I–II: 23, III–IV: 53	Tissue	hsa_circ_0001649	Decreased	/	/	/	/	/
Zhang et al[28], 2018	China	86	Early: 38, Late: 48	Tissue	circsMaD2	Decreased	/	/	/	/	/

circRNA: Circular RNA; OS: Overall survival; HR: Hazard ratio; NOS: Newcastle-Ottawa Scale; TNM: Tumor-node-metastasis.

Table 3 Study quality and bias in the retrospective cohort studies assessed via the Newcastle-Ottawa Scale checklist

Study	Cohort selection				Comparability	Outcome ascertainment
	Representativeness of the exposed cohort	Selection of the non-exposed cohort	Ascertain-ment of exposure	Demonstration that outcome of interest was not present at start of study	Comparability of cases and controls on the basis of the design or analysis	Assessment of outcome	Was follow-up long enough for outcomes to occur	Adequacy of follow up of cohorts
Cai et al[10], 2018	1	1	1	1	1	1	0	0
Zhong et al[30], 2018	1	1	1	1	1	1	0	0
Li et al[18], 2018	1	1	1	1	2	1	0	0
Weng et al[22], 2018	1	1	1	1	2	1	0	0
Chen et al[11], 2018	1	1	1	1	1	1	1	1
Gong et al[14], 2018	1	1	1	1	2	1	0	0
Yu et al[26], 2018	1	1	1	1	2	1	0	0
Huang et al[17], 2017	1	1	1	1	1	1	1	1
Han et al[16], 2017	1	1	1	1	2	1	0	0
Guo et al[15], 2017	1	1	1	1	1	1	0	0
Zhang et al[27], 2018	1	1	1	1	1	1	0	0

Table 4 Associations between circular RNA expression and clinicopathological factors in patients with hepatocellular carcinoma

Class	Included studies	χ2	Pooled P-value
Gender	18	36.426	0.4487
Age	18	32.517	0.635
Smoking (yes vs no)	5	8.597	0.5707
Alcoholism	5	19.684	0.0323
Tumor size	13	57.979	0.00012
Tumor number (single vs multiple)	7	14.3614	0.4231
Encapsulation (incomplete/complete)	3	3.8078	0.7026
Differentiation grade (well/moderate/poor)	11	66.9698	1.97 × 10−6
Microvascular invasion	3	19.261	0.003744
TNM stage	13	76.1066	2.51 × 10−7
HBsAg	7	14.4284	0.418306
Serum AFP	12	42.4249	0.0115
Metastasis	12	79.8852	6.35 × 10−8
ALT	3	5.4896	0.4827
AST	4	12.3545	0.1361
GGT	3	14.3614	0.4231
Cirrhosis (yes/no)	5	5.8236	0.8298

ALT: Alanine transaminase; AST: Aspartate transaminase; GGT: Gamma-glutamyl transpeptidase; AFP: Alpha fetoprotein; TNM: Tumor-node-metastasis; HbsAg: Hepatitis B surface antigen.

Table 5 Subgroup analysis conducted based on sample type, control type, and expression status among the diagnostic studies

Analysis	Included individual studies	Sensitivity 95%CI	Specificity 95%CI	PLR 95%CI	NLR 95%CI	DOR 95%CI	AUC	Heterogeneity
Sample type
Tissue	10	0.73 (0.70–0.77)	0.82 (0.78–0.84)	4.03 (2.98–5.46)	0.29 (0.19–0.43)	15.17 (8.42–27.34)	0.88	I2 = 73.9%, P = 0.0001
Plasma	3	0.79 (0.74–0.84)	0.65 (0.57–0.73)	2.33 (1.47–3.7)	0.28 (0.12–0.63)	8.93 (2.37–33.64)	0.72	I2 = 87.3%, P = 0.0004
Expression status
Up-regulated circRNAs	4	0.70 (0.62–0.78)	0.83 (0.76–0.89)	4.00 (2.71–5.91)	0.37 (0.28–0.50)	11.48 (5.90–22.33)	0.97	I2 = 21.2%, P = 0.2832
Down-regulated circRNAs	7	0.74 (0.70–0.77)	0.75 (0.71–0.78)	2.75 (2.16–3.5)	0.33 (0.22–0.49)	8.75 (5.31–14.43)	0.81	I2 = 70.4%, P = 0.0025
Control type
Chronic hepatitis/cirrhosis vs HCC	3	0.77 (0.72–0.81)	0.76 (0.71–0.81)	3.08 (2.49–3.80)	0.32 (0.25–0.41)	10.89 (7.51–15.78)	0.84	I2 = 0.0%, P = 0.5262
Adjacent non-cancerous liver tissue vs HCC	6	0.63 (0.57–0.68)	0.75 (0.69–0.81)	2.33 (1.44–3.75)	0.52 (0.40–0.69)	4.7 (3.12–7.08)	0.73	I2 = 0.0%, P = 0.4953

AUC: Area under the curve, PLR: Positive likelihood ratio; NLR: Negative likelihood ratio; DOR: Diagnostic odds ratio; HCC: Hepatocellular carcinoma.