TABLE 2.

Plasma cfDNA isolation and ctDNA sequencing methods used in the included studies on the clinical applications of cfDNA in EC

Included study	Spin protocol	Amount of plasma	Isolation kit	cfDNA amount	Sequencing methods
Pasternack et al. [42]	3000 rpm 10 min, 16,000 ×g 10 min	4 mL	QIAsymphony PAXgene blood ccfDNA kit (Qiagen)	12 ng (mean)	ddPCR and MiSeq
Wu et al. [47]	1600 ×g 15 min, 16,000 ×g 10 min	200 μL	Plasma circulating DNA kit (TIANGEN)	NR	SALP‐seq
Tian et al. [55]	1350 ×g 12 min, 13,500 ×g 12 min	NR	QiaAmp circulating nucleic acid kit (Qiagen)	NR	Nano‐hmC‐Seal
Ueda et al. [56]	2500 ×g 10 min, 16,000 ×g 10 min	NR	QiaAmp circulating nucleic acid kit (Qiagen)	NR	Targeted sequencing
Hagi et al. [58]	1600 ×g 10 min, 16,000 ×g 10 min	1.2 mL	QiaAmp circulating nucleic acid kit (Qiagen)	14.76‐50.76 ng	MiSeq and molecular barcode sequencing using Ion Torrent Proton sequencer
Egyud et al. [60]	1600 ×g 10 min, 3600 ×g 10 min	NR	QiaAmp circulating nucleic acid kit (Qiagen)	NR	ddPCR and SiMSen‐seq
Luo et al. [61]	1600 ×g 20 min	0.5 or 1 mL	QiaAmp circulating nucleic acid kit (Qiagen)	NR	Whole‐exome sequencing and targeted sequencing (TruSight Cancer panel)
Meng et al. [62]	900 ×g 10 min, 16,000 ×g 10 min	1‐3 mL	QiaAmp circulating nucleic acid kit (Qiagen)	4.86‐38.6 ng	Targeted sequencing
Azad et al. [63]	1800 ×g 10 min	NR	QiaAmp circulating nucleic acid kit (Qiagen)	NR	CAPP‐seq

cfDNA = circulating cell‐free DNA, ctDNA = circulating tumor DNA, NR = not reported, SALP‐seq = single‐strand adaptor library preparation sequencing, ddPCR = digital droplet polymerase chain reaction, SiMSen‐seq = simple multiplexed PCR‐based barcoding of DNA for sensitive mutation detection using sequencing, CAPP‐seq = cancer personalized profiling by deep sequencing. Nano‐hmC‐Seal is a highly sensitive and selective chemical labeling and capture approach for genome‐wide profiling of 5‐hydroxylmethylcytosine using DNA isolated from ∼1000 cells.