Free circulating DNA as possible tumour marker in colorectal cancer

Aim of the study: The purpose of this study is to evaluate the sensitivity and specificity of free circulating DNA (CFDNA) as a potential tumour marker in patients suffering from colorectal cancer (CRC). Materials and methods: The quantification of plasma DNA was determined through the use of real-time quantitative polymerase chain reaction (PCR) amplification of the RNAse P gene. We studied patients undergoing surgery for primary CRC, at different stages of disease and a cohort of comparable healthy donors. Data were statistically analysed using Student's t-test. Results: The mean DNA index of the tumour samples was 4771 ng/ml, about 50 times higher in comparison with healthy donors (mean value 0.85 ng/ml). In contrast the carcinoembryonic antigen (CEA) value of these patients was altered in only 47% of cases. Conclusion: This study shows that circulating free DNA levels in plasma of patients with CRC are significantly higher compared to healthy subjects, and suggest a new, non-invasive, approach for colon cancer detection and to identify high risk individuals for CRC screening.