Sometimes abnormal growths, called polyps, form in the colon or rectum. Over time, some polyps may turn into cancer. Screening tests can find polyps so they can be removed before turning into cancer. Screening also helps find colorectal cancer at an early stage, when treatment often leads to a cure.
Your risk of getting colorectal cancer increases as you get older. More than 90% of cases occur in people who are 50 years old or older. Other risk factors include having—
- Inflammatory bowel disease–such as Crohn’s disease or ulcerative colitis.
- A personal or family history of colorectal cancer or colorectal polyps.
- A genetic syndrome such as familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (Lynch syndrome).
Lifestyle factors which can contribute to an increased risk of colorectal cancer include—
- Lack of regular physical activity.
- A diet low in fruit and vegetables.
- A low-fiber and high-fat diet.
- Overweight and obesity.
- Alcohol consumption.
- Tobacco use.
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.
The U.S. Preventive Services Task Force found that taking low-dose aspirin can help prevent cardiovascular disease and colorectal cancer in some adults, depending on age and risk factors. For more information, download Aspirin Use for the Primary Prevention of Cardiovascular Disease and Colorectal Cancer: Consumer Guide. Some studies suggest that people may reduce their risk of developing colorectal cancer by increasing physical activity, limiting alcohol consumption, and avoiding tobacco.
Overall, the most effective way to reduce your risk of colorectal cancer is by having regular colorectal cancer screening tests beginning at age 50.
