Colonography Versus Colonoscopy in High Risk Patient

Inclusion Criteria: Surveillance of patients with a personal history of advanced adenoma or CRC: * Informed consent obtained * Age ≥ 18 and ≤ 80 years old * History of advanced adenomatous polyps * Or history of non metastatic CRC with curative surgery and without other treatment more than 2 years before enrollment. * Previous medical examination Screening of patients with a Family history of CRC at high risk: * Informed consent obtained * Age ≥ 18 and ≤ 80 years old * First degree family history of colorectal cancer diagnosed \<60yrs during the five previous years-Previous medical examination Exclusion Criteria: Personal histories * Age \< 18 or \>80 years old * history of non adenomatous polyps * history of Metastatic CRC * familial adenomatous polyposis, Peutz-Jeghers syndrome, hereditary non polyposis colorectal cancer (HNPCC), juvenile polyposis syndrome * Familial history of familial adenomatous polyposis * Personal history of subtotal colectomy (but not of hemicolectomy, to confer to inclusion criteria) * Colonoscopy with a polyps resection dated more than 5 years and less than 2 years prior to enrollment. * Enrollment in another protocol * no health insurance affiliation Family histories * Age \< 18 or \>80 years old * Patients with one or several family histories of first degree colorectal cancer occured to unknown age or diagnosed after 60 years old. * Eligible patients having already undergone colonoscopy screening * no health insurance affiliation