Circulating methylated DNA.

Early detection of cancer would facilitate better management of patients, because survival is greatly affected by stage of presentation. Circulating nucleic acids represent a biomarker that might be used in the early detection of cancer. In addition, such biomarkers could potentially be used to follow the progression of patients with cancer. DNA methylation of the promoter region CpG islands of genes represents one such nucleic acid-based marker, and possesses some advantages over other approaches. These include the stability of DNA as a molecule, the ability to detect such changes using simple polymerase chain reaction-based approaches, and the potential for methylated DNA to be preferentially present in nucleosomes in plasma or serum. These factors are presented and their impact on the detection of methylated DNA circulating in the bloodstream is demonstrated.