Free circulating DNA as a biomarker of colorectal cancer

Objectives: The purpose of this study is to evaluate the sensitivity and specificity of free circulating DNA (FCDNA) as a biomarker in patients suffering from colorectal cancer (CRC), investigating both its prognostic value correlated with stage of disease and its potential role in early recurrence diagnosis. Methods: The quantification of plasma DNA was achieved through the use of real time quantitative polymerase chain reaction (PCR) amplification of the RNAse P gene. The study enrolled patients undergoing surgery for primary CRC, at different stages of disease; samples were collected before surgery and during follow-up examinations every 3 months after surgery. Data were statistically analyzed using Software Packages SPSS® for Windows. Results: FCDNA was detectable in all pre-operative samples and the mean value was 47.8 ng/mL. FCDNA values increased progressively related to UICC stage of disease, although statistical significance was demonstrated only when comparing patients by pT stage. The analysis of postoperative samples showed a significant decrease of FCDNA quantity after radical surgery and in specific cases a rise preceding disease recurrence. Conclusions: This study shows that absolute quantification of FCDNA in CRC patients could have a prognostic value, being related to stage of disease, and could be used as potential tool for early detection of recurrences.