TABLE 2.

Clinical characteristics of BC patients in prognostic studies on circRNAs

Study	CircRNA expression		CircRNA type	Expression level	Test method	Reference gene	Survival point	Follow‐up time	HR extraction
	High	Low
Chen B 2018 20	83	157	circEPSTI1	Up‐regualted	qRT‐PCR	β‐actin	OS, DFS	Unclear	Indirectly
Zeng K 2018 34	82	83	circANKS1B	Up‐regualted	qRT‐PCR/2−△△Ct method	GAPDH	OS	Mentioned the follow‐up process	Directly
He R 2017 22	119	103	circGFRA1	Up‐regualted	qRT‐PCR/2−△△Ct method	β‐actin	OS, DFS	Unclear	Indirectly
Yang L 2019 31	29	28	Circ_0103552	Up‐regualted	qRT‐PCR/ΔCt	Unclear	OS	Unclear	Directly
Uhr K 2018 27	Total: 345		CDR1‐AS	Up‐regualted	qRT‐PCR/2−△△Ct method	Unclear	OS, PFS	Median: 91 mo	Directly
Xu JH 2019 29	75	70	has_circ_001569	Up‐regualted	qRT‐PCR/2−△△Ct method	GAPDH	OS	Unclear	Directly
Liu Z 2019 24	38	98	hsa_circ_001783	Up‐regualted	qRT‐PCR	β‐actin	OS	Unclear	Directly
Zhou H 2019 35	85	65	circFBXL5	Up‐regualted	Microarray analysis	/	OS	Unclear	Indirectly
Xu Y 2018 30	41	35	circ_0005230	Up‐regualted	qRT‐PCR/2−△△Ct method	GAPDH	OS	Unclear	Directly
Yang R 2019 32	20	20	circAGFG1	Up‐regualted	qRT‐PCR	Unclear	OS	Unclear	Directly
Wang S 2018 28	39	39	circ‐UBAP2	Up‐regualted	qRT‐PCR/2−△△Ct method	GAPDH, U6	OS	Unclear	Indirectly
Gao D 2019 21	49	48	circ_0006528	Up‐regualted	qRT‐PCR/2−△△Ct method	Unclear	OS, RFS	Unclear	Indirectly
Smid M 2019 26	Total: 348		circCNOT2	Up‐regualted	qRT‐PCR/2−△△Ct method	Unclear	PFS	Unclear	Directly

Abbreviations: DFS, disease‐free survival; GAPDH, reduced glyceraldehyde‐phosphate dehydrogenase; HR, hazard ratio; OS, overall survival; PFS, progression‐free survival; qRT‐PCR, quantitative reverse transcription‐polymerase chain reaction; RFS, relapse‐free survival.