Circulating-free DNA Assessment as a Tool to Predict Colorectal Cancer in Subjects With a Positive Fecal Immunoassay.

Colorectal cancer (CRC): is one of the most frequent cancers, with almost 42152 new cases estimated in France for 2012. There are 3 levels of risk of developing CRC: moderate, high or very high. At each level of risk, appropriate follow-up recommendations are made. Immunological tests for fecal occult blood tests have emerged in recent years and have rapidly become established as benchmark tests in Europe and then in France (OC Sensor test) as part of mass screening. In the case of a positive immunological test, a diagnostic colonoscopy must be systematically organized in order to characterize the possible recto-colic cause of the digestive bleeding thus observed. Measurement of the DNA present in the circulating blood (circulating DNA or cfDNA): allowed a significant advance in the personalized management of cancers, as a non-invasive test capable of producing diagnostic, prognostic, theranostic, and of therapeutic follow-up type. The aim of the work is to measure the cfDNA concentration in subjects undergoing colonoscopy because of a positive immunological fecal test.