Colorectal Cancer Screening

Colorectal cancer is one of the most preventable cancers because screening can find and remove precancerous polyps before they become cancer. Screening can also detect colorectal cancer at an early stage, when treatment is often more successful.

Most people should begin regular colorectal cancer screening at age 45, even if they have no symptoms. People with certain risk factors may need to begin screening earlier or be screened more often.

What is colorectal cancer screening?

Colorectal cancer screening means looking for colorectal cancer or precancerous polyps before symptoms develop. Most colorectal cancers begin as small growths called polyps that form in the lining of the colon or rectum. Over time, some polyps can become cancerous. Unlike many other cancer screening tests, colorectal cancer screening can prevent cancer by finding and removing these polyps before they develop into cancer. Screening is recommended even if you feel healthy and have no symptoms.

When should you start colorectal cancer screening?

For adults at average risk, most organizations recommend beginning regular colorectal cancer screening at age 45 and continuing through age 75. People between 76 and 85 years old should discuss the benefits and risks of continued screening with their healthcare provider based on their overall health and previous screening history. People at higher risk may need to begin screening before age 45 or undergo screening more frequently.

You may be at increased risk if you have

• A personal history of colorectal cancer or colon polyps

• A family history of colorectal cancer or advanced polyps

• Lynch syndrome, Familial Adenomatous Polyposis (FAP), or another inherited cancer syndrome

• Long-standing ulcerative colitis or Crohn's disease involving the colon

• A history of abdominal or pelvic radiation therapy

Talk with your healthcare provider about when you should begin screening and which screening schedule is right for you.

Which colorectal cancer screening test is right for you?

There is no single screening test that is best for everyone. The right choice depends on your age, personal risk factors, family history, medical conditions, and personal preferences. Several screening options are available. Some tests look for blood or abnormal DNA in the stool, while others examine the inside of the colon to look for polyps or cancer. Colonoscopy is considered the gold standard because it allows doctors to find and remove polyps during the same procedure. The most effective screening test is the one that gets done. Talk with your healthcare provider about which option is best for you.

Types of colorectal cancer screening tests

Colonoscopy

A colonoscopy uses a long, flexible tube with a camera to examine the entire colon and rectum. If polyps are found, they can often be removed during the procedure before they become cancerous. Tissue samples called biopsies can also be collected if needed. For people at average risk with normal findings, colonoscopy is typically repeated every 10 years.

Stool DNA Test (FIT-DNA)

The stool DNA test, also called a FIT-DNA test, looks for hidden blood and abnormal DNA that may come from colorectal cancer or advanced polyps. This test is completed at home and does not require bowel preparation or sedation. If the result is abnormal, a colonoscopy is needed to determine the cause.

Fecal Immunochemical Test (FIT)

The FIT test checks for tiny amounts of blood in the stool that cannot be seen with the naked eye. It is performed at home and is recommended every year for people at average risk. A positive FIT result should always be followed by a colonoscopy.

Guaiac Fecal Occult Blood Test (gFOBT)

The guaiac fecal occult blood test (gFOBT) also looks for hidden blood in the stool. Certain foods and medications may affect the results, so you may need to follow dietary instructions before testing. Like FIT, an abnormal result requires follow-up with a colonoscopy.

CT Colonography (Virtual Colonoscopy)

CT colonography uses a CT scan to create detailed images of the colon and rectum. This test does not require sedation, but bowel preparation is still necessary. If polyps or other abnormalities are found, a standard colonoscopy is needed to remove or biopsy them. CT colonography is typically recommended every five years for average-risk adults.

Flexible Sigmoidoscopy

Flexible sigmoidoscopy uses a thin camera to examine the rectum and lower portion of the colon. Because it does not examine the entire colon, it may miss cancers or polyps located higher in the colon. If abnormal findings are seen, a full colonoscopy is usually recommended.

What happens if a screening test is abnormal?

An abnormal screening result does not necessarily mean you have colorectal cancer. Many abnormal results are caused by noncancerous polyps, hemorrhoids, inflammation, or other conditions. If a stool-based screening test is abnormal, your healthcare provider will usually recommend a colonoscopy to determine the cause and remove any polyps if needed.

Why screening matters

Colorectal cancer often develops slowly over many years and may not cause symptoms until it is more advanced. Regular screening can:

• Find colorectal cancer before symptoms develop

• Detect cancer at an earlier, more treatable stage

• Find and remove precancerous polyps before they become cancer

• Reduce the risk of dying from colorectal cancer

Talk with your healthcare provider

If you are age 45 or older, or younger with increased risk factors, talk with your healthcare provider about colorectal cancer screening. Together, you can choose the screening test and schedule that best fit your personal risk and health history.