Potential prognostic, diagnostic and therapeutic markers for human gastric cancer

Table 1 Serum-based tumor markers in gastric cancer

Biological category	Biomarker (Gene name)	Cutoff level /Expression levels in human GC serum	Clinical significance	Associated tumor types	Ref.
Oncofetal antigen	CEA	5 μg/L	Prognosis	Gastrointestinal cancer	[24,25]
			GC progression monitoring	Cervix cancer
				Lung cancer
				Ovary cancer
				Breast cancer
				Urinary tract cancer
Glycoprotein antigen	CA19.9	37 kU/L	Prognosis	Mainly pancreatic cancer	[26]
			GC progression	but also colorectal cancer
			monitoring	other types of gastrointestinal cancer
	CA72.4	6 kU/L	Prognosis	Ovary cancer	[27]
			GC progression	Breast cancer
			monitoring	Colon cancer
				Pancreatic cancer
Cytokeratins	Cyfra21.1	Variable	Prognosis	Many types of carcinoma	[29]
				Some types of sarcoma
	TPA	Variable	Prognosis	Carcinoma	[30]
	TPS	Variable	Prognosis	Adult epithelial tumours	[30]
Hormone	Β subunit of hCG	4 μg/L	Prognosis	Seminoma	[31]
				Choriocarcinoma
				Germ cell tumors
				Choriocarcinoma
				Islet cell tumor
				Testicular cancer
Cell proliferation	Reg IV	Overexpression	Prognosis	Gastrointestinal malignancies	[33,34]
	Granulin	Overexpression	Prognosis	Gastrointestinal malignancies	[35,36]
Signaling protein	14-3-3 protein	Downexpression	Prognosis	Epithelial cancer	[40-42]
				Lung cancer
				Breast cancer
				Bladder cancer
				Liver cancer
				Oral cancer
				Head-and-neck squamous cell cancer
	DKK-1	Overexpression	Prognosis	Prostate cancer	[43-49]
				Breast cancer
				Colon cancer
				Esophageal cancer
				Lung cancer
				Multiple myeloma (MM)
Inflammatory	SAA	Overexpression	Prognosis	Lung cancer	[50,52,53]
				Kidney cancer
				Colon cancer
				Prostate cancer
				Liver cancer
Cell apoptosis	MG7-Ag	Overexpression	Prognosis	Gastrointestinal cancer	[55,56]
Enzyme	PG	Overexpression	Prognosis	Gastrointestinal cancer	[57]

CEA: Carcinoembryonic antigen; CA19-9: Carbohydrate antigen 19-9; CA72-4: Carbohydrate antigen 72-4; Cyfra21.1: Cytokeratin subunit 19 fragment; TPA: Tissue polypeptide antigen; TPS: Tissue polypeptide-specific antigen; β-hCG: β-subunit of human chorionic gonadotropin; Reg IV: Regenerating gene IV; Dkk-1: Dickkopf-1; SAA: Serum Amyloid A; MG7-Ag: Gastric cancer associated antigen; PG: Pepsinogens.