<unk> , also called cell-free<unk>  and circulating cell-free<unk>  DNA (ccf mtDNA), are short sections of<unk>  DNA (mtDNA) that are released by cells undergoing stress or other damaging or pathological events.<unk>  is recognized by the immune system and activates inflammatory reactions. It is also a biomarker that can be used to detect the degree of damage from myocardial infarctions, cancers and ordinary stress. In certain situations it acts as a hormone. Plasma or serum levels of ccf mtDNA have been seen to be of marked difference in people with cancer. These higher levels have shown to be a reliable non-invasive biomarker in the diagnosis and prognosis of many kinds of tumours. Specific analysis of tumor-derived<unk>  is challenging in human samples as it requires to track in plasma defined mutations, or alterations from the<unk>  genome. In animal models, separating tumor-derived DNA in plasma from non-tumor derived DNA is easier. A proof of principle demonstrated the sensitivity of detecting tumor-derived<unk>  in the plasma, CSF and urine of xenografted animals.
Circulating mitochondrial DNA
Circulating tumor DNA
Cell-free fetal DNA
Oncogenic retroviridae protein
Epstein–Barr virus viral-capsid antigen
Cross-reactive carbohydrate determinants
Persistent polyclonal B-cell lymphocytosis
Anton blood group antigen