The rational for this examination is that the large majority of malignant tumors arise from colon polyps, and that the malignant transformation into cancer usually takes several years. If a colon polyp is detected in time, it can be removed in one and the same colonoscopy session, and thus occurrence of large bowel cancer can be prevented.
Preventative colonoscopy should start in the 5 th decade. If there are no pathological findings, it should be repeated in about 8 to 10 years. In case of colon polyps and the grade of dysplasia in the removed tissue a control colonoscopy should be done in a shorter period of time. The gastroenterologist / endoscopist will let you know.
There are no real good alternatives to a preventative colonoscopy. Tests for blood in the stool are limited by the fact that polyps usually do not bleed. Most commonly these tests are only positive when colorectal cancer has already developed.