Quantification of free circulating tumor DNA as a diagnostic marker for breast cancer.

Aim: To determine whether the amounts of circulating DNA could discriminate between breast cancer patients and healthy individuals by using real-time PCR quantification methodology.

Methods: Our standard protocol for quantification of cell-free plasma DNA involved 175 consecutive patients with breast cancer and 80 healthy controls.

Results: We found increased levels of circulating DNA in breast cancer patients compared to control individuals (105.2 vs. 77.06 ng/mL, p < 0.001). We also found statistically significant differences in circulating DNA amounts in patients before and after breast surgery (105.2 vs. 59.0 ng/mL, p = 0.001). Increased plasma cell-free DNA concentration was a strong risk factor for breast cancer, conferring an increased risk for the presence of this disease (OR, 12.32; 95% CI, 2.09-52.28; p < 0.001).

Conclusions: Quantification of circulating DNA by real-time PCR may be a good and simple tool for detection of breast cancer with a potential to clinical applicability together with other current methods used for monitoring the disease.