Cell-free Serum DNA in Patients with Bladder Cancer: Results of a Prospective Multicenter Study

Background/Aim: Cell-free DNA may serve as a biomarker for patients with cancer; we designed our study to determine its potential in patients with bladder cancer (BCA). Materials and Methods: Short β-actin (ACTB)-106 and large ACTB-384 fragments were quantified using real time PCR (RT-PCR); the ratio of ACTB-384/ACTB-106 was defined as DNA integrity. We analyzed the serum from 95 patients with and from 132 without BCA. Results: Patients with BCA had increased ACTB-106 levels and lower DNA integrity compared to patients without cancer. However, patients undergoing transurethral bladder resection (TURB) with histological exclusion of BCA had a similar ACTB-106 level and DNA integrity, as patients with BCA. Cell-free DNA was not correlated with smoker status, pT stage, grade or lymph node metastasis, or DNA integrity. There was a weak inverse correlation of age with DNA integrity in patients with BCA. Conclusion: Analysis of serum cell-free DNA levels and fragmentation patterns are of limited value regarding the identification of patients with BCA. The existence of cell-free DNA in blood was discovered as early as the 1940s (1), but its potential for diagnosis, prognosis and monitoring of cancer patients was unrealised. The implementation of easy and less-expensive detection methods permitted for extensive research on the diagnostic and prognostic role of cell-free DNA, and in recent years a number of studies reported higher levels of cell-free DNA in plasma/serum of patients with various tumour entities (ovarian cancer (2), breast cancer (3), lung cancer (4), prostate cancer (5), renal cell carcinoma (6), gastric cancer (7), esophageal cancer (8)), which allowed there to be differentiated from healthy individuals and patients with non- malignant diseases. Furthermore, high levels of cell-free DNA were found to be indicative of poor prognosis (lung cancer (4); prostate cancer (5, 9)). It was also recognized that cell- free DNA in cancer patients and healthy controls is differently sized: some studies reported an increase (breast cancer (10), colorectal cancer (11), renal cell carcinoma (12)), whereas others reported a decrease (prostate cancer (13), testicular cancer (14)) of DNA integrity in cancer patients. Similarly to quantitative changes, fragmentation patterns were also useful for prognosis (10, 13). There is no biomarker, in addition to urine cytology, used in daily routine for the diagnostic work-up of patients suspected of having bladder cancer (BCA). We reported that cell-free DNA levels and the DNA integrity allowed for patients with BCA to be identified, however, that cohort consisted only of patients undergoing radical cystectomy (15). The aim of the present study was to analyze cell-free DNA levels and fragmentation patterns in patients with non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC).