Levels of circulating cell-free serum DNA in benign and malignant breast lesions.

We analyzed circulating cell-free DNA in the serum of patients with benign and malignant breast disease and in healthy individuals to determine its diagnostic value. Serum samples were obtained from 50 healthy individuals, 33 patients with malignant breast disease and 32 patients with benign breast disease. Circulatory DNA was extracted from serum samples. Cell-free DNA was quantified by real-time quantitative PCR for the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. Tissue samples from patients with malignant and benign breast lesions were histopathologically examined. The mean levels of circulating cell-free DNA in serum samples were 41,149 genome equivalents (GE)/mL in patients with malignant disease, 30,826 GE/mL in patients with benign disease, and 13,267 GE/mL in healthy individuals. Healthy individuals had significantly lower levels of cell-free DNA than patients with malignant or benign breast disease (p=0.001, p=0.031). No significant difference was observed between malignant and benign disease. There was a correlation between cell-free DNA levels and tumor size but not with other tumor characteristics. Our results suggest that levels of circulating cell-free DNA in serum could have diagnostic value to discriminate between healthy individuals and patients with breast lesions but not between patients with malignant and benign breast lesions.