Colonic polyps are common especially in people over the age of 60. Most such patients will have only a few colonic polyps, usually less than 10 and in these cases the inherited risk is not great. However in a few patients many colonic polyps develop, starting as young as ten years old. So by the age of 20 the colon has at least one hundred and sometimes thousands of polyps. These polyps are called adenomas and have the risk of developing into colon cancer. Although each individual polyp has a fairly low risk of becoming malignant the patient has so many polyps that colon cancer is almost inevitable by the age of 40 to 50 years.