Circulating cell-free DNA variables as marker of ovarian cancer patients: A pilot study

BACKGROUND: Minimal invasive blood-based molecular markers are evaluated as promising biomarkers in malignant diseases these days. OBJECTIVE: In this pilot study, we investigated the potential of cell-free DNA (cfDNA) concentration and cell-free DNA Integrity (cfDI) as blood-based diagnostic markers for ovarian cancer patients in a retrospective study cohort. METHODS: cfDNA concentration and cfDI were determined in the plasma of 37 ovarian cancer patients and 28 healthy controls, by measuring ALU and LINE1 repetitive DNA elements using quantitative real-time PCR. RESULTS: A high correlation was observed between the results of ALU and LINE1. The correlated co-efficiency between the values of cfDNA concentration and cfDI was 0.86 and 0.71. As for the results between cases and controls, no or just borderline significant difference was observed in cfDI after age adjustment (P = 0.40 for ALU and P = 0.05 for LINE1) while cfDNA concentration showed a significant difference between ovarian cancer patients and healthy controls groups (P = 0.03 for ALU and P = 3.00 E-03 for LINE1). cfDNA concentration of ALU and LINE1 had an AUC of 0.81 (0.70-0.91). ALU and LINE1 cfDI reached an AUC of 0.60 (95% CI: 0.46-0.73). The combination of these markers reached the best diagnostic power with an AUC of 0.84. CONCLUSIONS: cfDNA variables might be potentially diagnostic biomarkers in ovarian cancer, in combination with additional molecular markers. However, further studies are needed to confirm the diagnostic ability of cfDNA variables (cfDNA concentration and cfDI).