Human blood contains cell free DNA (cfDNA), small fragments of DNA originating from cellular breakdown of healthy cells. In cancer patients, a tiny fraction of circulating tumor DNA (ctDNA) shedded from cancer cells maybe present among the huge number of cfDNA fragments. ctDNA contains mutations which match the mutations in the cancer cells they are originating from, e.g. disseminated cells.

Thus, the population of ctDNA in the blood of a patient resembles a characteristic tumor- and patient specific fingerprint. As the half-life of cfDNA / ctDNA in circulation is less than two hours, real time tumor dynamics can be tracked hereby informing about the current state of the disease. The presence of ctDNA in the blood is prognostic and ctDNA analysis can be used e.g. to detect minimal residual disease to monitor treatment response or to identify actionable targets for personalized treatment approaches.

Karin Birkenkamp-Demtröder

Karin Birkenkamp-Demtröder, M.Sc., Ph.D og Associate Professor ved Aarhus Universitet