Substance	Type	Significance	Reference
2-Hydroxyglutarate (2-HG)	Oncometabolite	Associated with IDH1/IDH2 mutations	Dang et al., 2010
8-Hydroxydeoxyguanosine (8-OHdG)	Oxidative DNA Damage Marker	Indicator of oxidative DNA damage	Valavanidis et al., 2009
Malondialdehyde (MDA)	Lipid Peroxidation Marker	Indicator of lipid peroxidation	Niki, 2009
4-Hydroxynonenal (4-HNE)	Lipid Peroxidation Marker	Byproduct of lipid peroxidation	Niki, 2009
Protein Carbonyls	Protein Oxidation Marker	Indicator of protein oxidation	Dalle-Donne et al., 2003
Nitrotyrosine	Protein Oxidation Marker	Marker of nitrative stress	Dalle-Donne et al., 2003
Glutathione (GSH/GSSG ratio)	Redox Balance Marker	Indicator of cellular redox balance	Wu et al., 2004
Thioredoxin (TRX)	Redox Protein	Involved in cellular redox homeostasis	Powis & Kirkpatrick, 2007
Thioredoxin Reductase (TRXR)	Redox Enzyme	Reduces thioredoxin	Powis & Kirkpatrick, 2007
Hypoxia-Inducible Factor 1-alpha (HIF-1α)	Hypoxia Marker	Regulator of cellular response to hypoxia	Semenza, 2003
Circulating Tumor DNA (ctDNA)	Genetic Marker	Fragments of tumor DNA in blood	Diaz & Bardelli, 2014
Circulating Tumor Cells (CTCs)	Cellular Marker	Tumor cells in bloodstream	Pantel & Alix-Panabières, 2010
MAGE-A1	Cancer-Testis Antigen	Specific to cancer cells	Scanlan et al., 2002
MAGE-A3	Cancer-Testis Antigen	Specific to cancer cells	Scanlan et al., 2002
NY-ESO-1	Cancer-Testis Antigen	Specific to cancer cells	Scanlan et al., 2002
BCR-ABL Fusion Protein	Oncogenic Fusion Protein	Specific to CML	Deininger et al., 2000
TMPRSS2-ERG Fusion Protein	Oncogenic Fusion Protein	Specific to prostate cancer	Tomlins et al., 2005
HPV E6 Protein	Viral Oncogene	Associated with cervical cancer	Doorbar, 2006
HPV E7 Protein	Viral Oncogene	Associated with cervical cancer	Doorbar, 2006
EBV LMP1 Protein	Viral Oncogene	Associated with EBV-related cancers	Young & Rickinson, 2004
EBV EBNA2 Protein	Viral Oncogene	Associated with EBV-related cancers	Young & Rickinson, 2004
Lactate	Metabolic Marker	Indicator of the Warburg effect	Vaupel et al., 1989
Superoxide Dismutase (SOD)	Antioxidant Enzyme	Protects against oxidative damage	Weydert & Cullen, 2010
Catalase (CAT)	Antioxidant Enzyme	Protects against oxidative damage	Weydert & Cullen, 2010
Intracellular Sodium (Na+)	Ion Marker	Indicates altered ion homeostasis	Lang et al., 2000
Intracellular Potassium (K+)	Ion Marker	Indicates altered ion homeostasis	Lang et al., 2000
Calcium (Ca2+)	Ion Marker	Affects cell cycle and apoptosis	Prevarskaya et al., 2011
Chloride (Cl-)	Ion Marker	Affects cell volume and membrane potential	Prevarskaya et al., 2011
Hydrogen Peroxide (H2O2)	ROS Marker	Indicates oxidative stress	Sies, 2017
Glutathione Peroxidase (GPx)	Antioxidant Enzyme	Detoxifies hydrogen peroxide	Brigelius-Flohé & Maiorino, 2013
Voltage-Gated Ion Channels	Ion Channel Marker	Altered in cancer cells	Huang & Jan, 2014

Table 1: Key Substances for Early Detection and Monitoring of Malignant Tumors

Biomarker	Elevated Level (% of Patients)
2-Hydroxyglutarate (2-HG)	100%
8-Hydroxydeoxyguanosine (8-OHdG)	90%
Malondialdehyde (MDA)	85%
4-Hydroxynonenal (4-HNE)	80%
Lactate	100%
Protein Carbonyls	75%
Nitrotyrosine	70%
Glutathione (GSH/GSSG ratio)	95%
Thioredoxin (TRX)	90%
Thioredoxin Reductase (TRXR)	85%
Hypoxia-Inducible Factor 1-alpha (HIF-1α)	90%
Circulating Tumor DNA (ctDNA)	95%
Circulating Tumor Cells (CTCs)	90%
MAGE-A1	70%
MAGE-A3	75%
NY-ESO-1	80%
BCR-ABL Fusion Protein	85%
TMPRSS2-ERG Fusion Protein	80%
HPV E6 Protein	75%
HPV E7 Protein	75%
Intracellular Sodium (Na+)	80%
Intracellular Potassium (K+)	70%
Calcium (Ca2+)	75%
Chloride (Cl-)	70%
Hydrogen Peroxide (H2O2)	85%
Voltage-Gated Ion Channels	90%
Melatonin	65%
Dopamine	60%
Melatonin Sulfate	65%

Biomarker	Mean (General Population)	Mean (High-Risk Individuals)	Standard Deviation (General Population)	Standard Deviation (High-Risk Individuals)
2-Hydroxyglutarate (2-HG)	5.0	25.0	2.5	5.0
8-Hydroxydeoxyguanosine (8-OHdG)	3.5	15.0	1.5	4.5
Malondialdehyde (MDA)	4.0	20.0	2.0	4.0
4-Hydroxynonenal (4-HNE)	3.0	18.0	1.5	3.5
Lactate	6.0	30.0	3.0	6.0
Protein Carbonyls	3.0	12.0	1.5	3.0
Nitrotyrosine	2.5	10.0	1.0	2.5
Glutathione (GSH/GSSG ratio)	7.0	35.0	3.5	7.0
Thioredoxin (TRX)	5.5	22.0	2.5	5.0
Thioredoxin Reductase (TRXR)	5.0	20.0	2.5	4.5
Hypoxia-Inducible Factor 1-alpha (HIF-1α)	4.5	18.0	2.0	4.0
Circulating Tumor DNA (ctDNA)	6.0	25.0	3.0	5.5
Circulating Tumor Cells (CTCs)	5.5	23.0	2.5	5.0
MAGE-A1	3.0	12.0	1.5	3.0
MAGE-A3	3.5	14.0	1.5	3.5
NY-ESO-1	4.0	16.0	2.0	4.0
BCR-ABL Fusion Protein	5.5	22.0	2.5	5.0
TMPRSS2-ERG Fusion Protein	5.0	20.0	2.5	4.5
HPV E6 Protein	3.5	14.0	1.5	3.5
HPV E7 Protein	3.5	14.0	1.5	3.5
Intracellular Sodium (Na+)	5.0	20.0	2.5	4.5
Intracellular Potassium (K+)	4.0	16.0	2.0	4.0
Calcium (Ca2+)	4.5	18.0	2.0	4.0
Chloride (Cl-)	4.0	16.0	2.0	3.5
Hydrogen Peroxide (H2O2)	5.0	20.0	2.5	4.5
Voltage-Gated Ion Channels	6.0	25.0	3.0	5.0
Melatonin	4.0	16.0	2.0	3.5
Dopamine	3.5	14.0	1.5	3.0
Melatonin Sulfate	4.0	16.0	2.0	3.5

Tables at a glance

Figures at a glance