Cell-free plasma DNA as biochemical biomarker for the diagnosis and follow-up of prostate cancer patients.

The aim of this study was to evaluate the diagnostic and potential prognostic value of cell-free plasma DNA (CF-pDNA) in patients with suspected or histologically proven prostate cancer (PCa). We included 133 men with a diagnosis of PCa and 33 controls. PCa patients had blood samples prospectively drawn every 3 months for 2 years. CF-pDNA was measured by spectrophotometry. Considering a cut-off value of 140 ng/mL of CF-pDNA the area under the curve was of 0.824(0.757-0.879 with a sensitivity = 66.2 % and a specificity = 87.9 %) and the positive and negative likelihood ratio were of 5.46 and 0.39, respectively. CF-pDNA tends to decrease slightly and return to baseline values in about a week after biopsy. There was no statistical significant correlation between CF-pDNA levels at study entry with PSA, Gleason score, stage and biochemical recurrence free survival (BRFS). However, with a mean follow-up of 13.5 months, we could observe a significant shorter BRFS for patients with at least one value above 140 ng/mL of CF-pDNA during follow-up (p = 0.048). CF-pDNA is a potentially valuable biomarker for PCa diagnosis and a potential tool for the follow-up of patients with PCa.