Circulating cell-free DNA integrity as a diagnostic and prognostic marker for breast and prostate cancers

Cancer incidence and its related mortality is rising and is currently the second leading cause of death globally. In Africa, breast and prostate cancer in females and males, respectively, are the worst globally. However, biomarkers for their early detection and prognosis are not well developed. This study sought to investigate circulating cell-free DNA (ccfDNA) integrity and its potential utility as diagnostic and/or prognostic biomarker. Circulating cell-free DNA (ccfDNA) is degraded DNA fragments released into the blood plasma. In healthy individuals, the source of ccfDNA is solely apoptosis, producing evenly sized shorter DNA fragments. In cancer patients, however, necrosis produces uneven longer cell-free DNA fragments in addition to the shorter fragments originating from apoptosis. DNA integrity, expressed as the ratio of longer fragments to total DNA, may be clinically useful for the detection of breast and prostate cancer progression.

Sixty-four (64) females, consisting of 32 breast cancer patients and 32 controls, and 61 males (31 prostate cancer patients and 30 controls) were included in the study. Each participant donated 5 ml peripheral blood from which sera were separated. Real-time qPCR was performed on the sera to quantify ALU 115 and 247 levels, and DNA integrity (ALU247/ALU115) determined.

ALU species 115 and 247 levels in serum were elevated in breast and prostate cancer patients compared to their counterpart healthy controls. DNA integrity was higher in prostate cancer patients than in the control, but in breast cancer patients was lower compared to their controls. In prostate but not in breast cancers, DNA integrity increased with disease severity and higher staging.