Colorectal cancer is a disease in which cells in the colon or rectum grow out of control. Sometimes it is called colon cancer, for short. The colon is the large intestine or large bowel. The rectum is the passageway that connects the colon to the anus.
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 works best.
What Is Colorectal Cancer Screening?
A screening test is used to look for a disease when a person doesn’t have symptoms. (When a person has symptoms, diagnostic tests are used to find out the cause of the symptoms.)
Colorectal cancer almost always develops from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find precancerous polyps, so that they can be removed before they turn into cancer. Screening tests can also find colorectal cancer early, when treatment works best.
Screening Recommendations
Regular screening, beginning at age 45, is the key to preventing colorectal cancer and finding it early. The U.S. Preventive Services Task Force (Task Force) recommends that adults age 45 to 75 be screened for colorectal cancer. The Task Force recommends that adults age 76 to 85 talk to their doctor about screening.
The Task Force recommends several colorectal cancer screening strategies, including stool tests, flexible sigmoidoscopy, colonoscopy, and CT colonography (virtual colonoscopy). Learn about these screening tests.
When Should I Begin to Get Screened?
Most people should begin screening for colorectal cancer soon after turning 45, then continue getting screened at regular intervals. However, you may need to be tested earlier than 45, or more often than other people, if you have—
- 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).
If you think you are at increased risk for colorectal cancer, speak with your doctor about—
- When to begin screening.
- Which test is right for you.
- How often to get tested.
If you have any of these symptoms, talk to your doctor. They may be caused by something other than cancer. The only way to know what is causing them is to see your doctor.
Last Reviewed: February 23, 2023
Source: Division of Cancer Prevention and Control, Centers for Disease Control and Prevention