Validation of an Alternative Biological Test to Increase the Detection Sensitivity of a Colon Tumour

This study search to validate a test by taking advantage of the biotechnical expertise from renowned academic research teams and mass screening organisation. In order to reduce the cost of the present study the investigators will select in this preliminary study only those individuals who have a FOBT. However, we'll measure the blood level by using a I-FOBT test to quantify Haemoglobin concentration in stools. Furthermore, we'll use stool DNA to characterize microbiota according to the colonoscopy findings. In addition, the investigators believe it is important to include in the project, the creation of biological blood and urine collections from individuals having undergone both faecal tests and a reference colonoscopy. In the future, these collections will be made available to the national or international scientific community (after consent by the principal investigators) to validate any other molecular and/or protein marker including proteomic analysis by using MSS. The investigators will perform methylated DNA test in either stools or blood and will compare results to those of I-FOBT and colonoscopy. A simplified molecular test based on a combination of the search for methylation anomalies (one PCR and/or dedicated microarray) a limited number of gene targets involved in colorectal carcinogenesis is available. The investigators will collect stools, urine, and blood in a period of 15 to 2 days prior to colonoscopy. The colonoscopy is performed in 50-74 years old asymptomatic individuals who have presented with a positive FOBT test under mass screening organisation. A final point will be performed 5 years after entry in the trial for all 1000 individuals in order to check occurrence (alternative absence) of any disease during this period and the type of the disease for those individuals who will be shown with normal colonoscopy and to verify evolution of those who will presented with a colon or rectal tumor. Likelihood value of marker in diseases occurring during the survey period will be calculated and prognostic values estimated in those with colon or rectal cancer.