Integrity and Quantity Evaluation of Plasma Cell-Free DNA in Triple Negative Breast Cancer

Triple-Negative Breast Cancer (TNBC) is a subtype of breast cancer that lacks expression of the estrogen and progesterone receptor and does not overexpress human epidermal growth factor 2 receptor protein. TNBC is associated with special characteristics, including aggressiveness, poor prognosis, and treatment response. Non-invasive blood-based molecular markers such as cell-free DNA (cfDNA) variables have been shown to be putative markers in breast cancer prognosis.

The cfDNA quantity and integrity were assessed in a case-control study of 96 breast cancer patients including 46 triple negative and 50 non-triple negative compared with 50 unaffected controls. A quantitative real-time PCR approach based on the quantification of two amplicons of the β-actin gene with different lengths (99 and 394 bp) was used to evaluate the integrity index 394/99.

Both cfDNA integrity index and quality were significantly elevated in breast cancer patients but integrity index can be considered as the more reliable diagnostic marker. The statistically significant increase of cfDNA quantity and integrity was observed in TNBC patients, somehow associated with nodal metastasis (p<0.001).

Elevated cfDNA concentration and integrity index in breast cancer patients compared with normal control and significant difference observed between TNBC and non-TNBC may be considered as a possible effective non-invasive diagnostic and prognostic molecular marker in breast cancer.