Almost all colorectal cancers begin as precancerous polyps (abnormal growths) in the colon or rectum. Such polyps can be present in the colon for years before invasive cancer develops. They may not cause any symptoms. Colorectal cancer screening can find precancerous polyps so they can be removed before they turn into cancer. In this way, colorectal cancer is prevented. Screening can also find colorectal cancer early, when there is a greater chance that treatment will be most effective and lead to a cure.
Research is underway to find out if changes to your diet can reduce your colorectal cancer risk. Medical experts don’t agree on the role of diet in preventing colorectal cancer, but often recommend a diet low in animal fats and high in fruits, vegetables, and whole grains to reduce the risk of other chronic diseases, such as coronary artery disease and diabetes. This diet also may reduce the risk of colorectal cancer. Also, researchers are examining the role of certain medicines and supplements in preventing colorectal cancer.