Extracellular DNA in breast cancer: Cell-surface-bound, tumor-derived extracellular DNA in blood of patients with breast cancer and nonmalignant tumors.

A methylation-specific polymerase chain reaction technique was used to investigate aberrant promoter methylation of RASSF1A and HIC-1 genes in circulating extracellular DNA (exDNA) from the blood of breast cancer and fibroadenoma patients. Methylated DNA could be detected in the exDNA eluted from the surface of erythrocytes and leukocytes, even in the samples where no methylated DNA could be detected in plasma. The data obtained demonstrate that cell surface bound exDNA provides a valuable source of material for early noninvasive cancer diagnostics and monitoring.