The investigators designed a prospective study to evaluate the predictive ability of detection of mutations in genes involved in carcinogenesis of the colon (eg hMLH1, K-Ras, B-Raf, ccfDNA) in a sample of Greek population presents for conducting colonoscopy in the context of screening under international CRC prevention instructions. This investigation will be carried out in individuals in normal risk in order to study specific mutations (in blood and tissue) to draw reliable conclusions about whether we can detect (with greater sensitivity and specificity) patients with precancerous lesions or CRC with a simple blood test thereby reducing the cost and side effects of repeated endoscopic procedures.