Table 1.

Cell-free DNA in oral squamous cell carcinoma patients

Name of the author, years, references	CfDNA	Sample type	Size of sample	Detection method	Observations
cfDNA as a detection and diagnostic markers
Shukla et al., 2013[2]	CfDNA	Saliva and plasma	390 patients (90 potentially malignant lesions, 150 OSCCs and 150 posttreatment OSCCs)	Spectrophotometry	No significant difference between groups
Mazurek et al., 2016[39]	HPV 16/18 KRAS, EGFR	Plasma	200 HNSCC patients	qPCR	96.4% positivity for HPV. No somatic mutation detection
Wang. Y et al., 2015[19]	TP53, PIK3CA, CDKN2A, HRAS, NRAS, HPV 16-18	Saliva and plasma	93 HNSCC	Digital PCR	HPV 16 positivity 76% in saliva 86% in plasma
Schröck et al., 2017[3]	Methylation markers SOX2 and SPET9	Saliva and plasma	649 HNSCC	qPCR	59% positivity
cfDNA as a prognostic and metastatic markers
Lin et al., 2018[40]	cfDNA	Plasma	121 OSCC and 50 matched control	Spectometry	cfDNA associated with tumoral size and poor prognosis of OSCC
Hamana et al., 2005[41]	Nine microsatellite markers	Tissue and serum	64 SCC patients	PCR	Allelic serum imbalance was 44% and 20% in pre-and post-operation
Kakimoto et al.,2008[42]	Microsatellite markers	Tissue and serum	20 OSCC patients	PCR	90% alleilic imbalance in serum and associated with poor prognosis of patients

OSCCs: Oral squamous cell carcinomas, cfDNA: Cell-free DNA, HNSACC: Head and neck squamous cell carcinomas, qPCR: Quantitative polymerase chain reaction, HPV: Human papillomavirus, KRAS: Kirsten rat sarcoma 2 viral oncogene homolog, EGFR: Epidermal growth factor receptor, HRAS: Harvey rat sarcoma viral oncogene homolog, NRAS: Neuroblastoma RAS viral oncogene homolog