Colo-rectal cancer (CCR) is one of the most prevalent cancers in developed countries. Several studies suggest that the CCR may be related with changes in the gut microbiota. This clinical trial is focused in the development of a screening test for the people at risk of CCR (aged more than 50 years old), valid and safe, improving the screening prognosis. The main potential improvement lies in the fact that the proposed method is more specific and sensitive than the current method, fecal occult blood. It aims to distinguish whether the positive results for fecal occult blood test is due to fissures, not related with CCR (which are positive for fecal occult blood, false positive) or was caused by a cancer-related lesion. The methodology derived will also improve the sensitive as sometimes the polyps do not leak blood. Based in the previous differences found in the gut microbiota composition related with CCR for several research groups, the gut microbiota composition will be used as diagnosis tool.
