Colorectal Cancer Screening

Risk factors for colorectal cancer

Your risk of having colorectal cancer is higher if you:

• Are older. Older adults are most likely to get colorectal cancer. But it can occur at any age.

• Have a family history or personal history of colorectal cancer or polyps.

• Are African American.

• Are of Eastern European Jewish descent (Ashkenazi).

• Have inflammatory bowel disease (Crohn’s disease or ulcerative colitis).

• Have cystic fibrosis.

• Have type 2 diabetes.

• Have an inherited genetic syndrome, such as Lynch syndrome or familial adenomatous polyposis.

• Are overweight or obese.

• Are not physically active.

• Smoke tobacco.

• Drink a lot of alcohol (more than 2 drinks per day for men and 1 drink per day for women).

• Eat a lot of red or processed meat.

The colon and rectum

The colon and rectum are part of your digestive system. Food goes from your stomach to your small intestine. It then goes into your colon. As it travels through the colon, water is removed. The waste that is left (stool) becomes more solid. The muscles of your intestines push the stool toward the sigmoid colon. This is the last part of the colon. The stool then moves into the rectum. The stool is stored there until it’s ready to leave your body.

How colorectal cancer starts

Polyps are growths that can form on the inner lining of the colon and rectum. Most are benign. This means they aren’t cancer. But over time, some polyps can become cancer. These are called malignant. This happens when cells in these polyps start to grow out of control. In time, the cancer cells can spread to more of the colon and rectum. The cancer can spread to nearby organs or lymph nodes. It can spread to other parts of the body, like the liver or lungs. Finding and removing polyps early can help keep cancer from starting.

Colorectal cancer screening

Screening means looking for a health problem before you have symptoms. Screening for colorectal cancer starts with:

• Your health history. Your doctor will ask about your health history. They will ask you about cancer risk factors that you may have. Tell your doctor if you have a family member who had colorectal cancer or polyps. Tell them about any health problems you had in the past.

• Screening tests. The American Cancer Society and the U.S. Preventive Services Task Force advise colorectal cancer screening for people at average risk starting at age 45. Talk with your doctor about your risks. Ask when you should start screening tests. It's also important to check with your health insurer about your coverage.

Types of screening tests

Below are the most common types of colorectal cancer screening tests. How often you should be screened depends on your risk. It also depends on the test that you and your doctor choose. If you have a family history of colon cancer or are at high risk for other reasons, you may need to have screening earlier. And you may need to have it more often.

Stool testing

Fecal occult blood test (FOBT) or fecal immunochemical test (FIT) (every year)

These tests check for blood in stool that you can’t see. This is called hidden or occult blood. Hidden blood may be a sign of colon polyps or cancer. A small sample of stool is sent to a lab where it's tested for blood. Most often, you collect this sample at home using a kit your doctor gives you. Make sure you know what to do and follow the directions carefully. For example, you might need to not eat certain foods and not take some medicines before collecting stool for this test. If you have an abnormal FOBT or FIT, you will likely need a colonoscopy.

Multi-targeted stool DNA test (every 3 years)

This test looks for cells in your stool that have abnormal DNA in them. These DNA changes might be signs of cancer or polyps. This test also looks for hidden blood in stool. For this test, you collect an entire bowel movement. This is done using a container that's put in the toilet. The kit has directions on how to collect, prepare, and send your stool. It goes to a lab for testing. If you have an abnormal result on stool DNA, you will likely need a colonoscopy.

Visual exams

Colonoscopy (every 10 years)

This test lets your doctor find and remove growths or polyps in your colon or rectum. It is the only screening test that lets your doctor see your entire colon and rectum. This test lets your doctor remove pieces of tissue that need to be checked for cancer.

One or 2 days before the test, you'll do a bowel prep. The bowel prep cleans out your colon. This is so the lining can be seen during the test. You'll be given directions on how to do the prep. It will include a liquid diet. You will then use a strong laxative solution or an enema.

Just before the test, you're given medicine to make you sleepy. Then the doctor gently puts a long, flexible, lighted tube (colonoscope) into your rectum. The scope is guided through your entire colon. The doctor looks at images of the inside of your colon on a video screen. Any growths or polyps seen are removed. They are sent to a lab for testing. If a polyp can’t be removed, a small piece of it is taken out for testing. If the tests show it might be cancer, the polyp might be removed later during surgery.

Flexible sigmoidoscopy (every 5 years)

This test is a lot like a colonoscopy. But it is done only on the sigmoid colon and rectum. The sigmoid colon is the last 2 feet or so that connects to your rectum. The entire colon is about 5 feet long.

One or 2 days before the test, you'll do a bowel prep. The bowel prep cleans out your colon. This is so the lining can be seen during the test. You'll be given directions on how to do the prep. It will include a liquid diet. You will then use a strong laxative solution or an enema.

You are awake during the test. But you may be given medicine to help you relax. The doctor guides a thin, flexible, lighted tube (sigmoidoscope) into your rectum and lower colon. The images are shown on a video screen. Polyps or growths can be removed. They are sent to a lab for testing.

Another choice is flexible sigmoidoscopy every 10 years, with a FIT stool test every year. Talk with your doctor to learn more.

Virtual colonoscopy (every 5 years)

This test is also called a CT colonography. It uses a series of X-rays. They make a 3-D image of your colon and rectum.

One or 2 days before the test, you'll do a bowel prep. The bowel prep cleans out your colon. This is so the lining can be seen during the test. You'll be given directions on how to do the prep. It will include a liquid diet. You will then use a strong laxative solution or an enema.

During the test, you'll lie on a narrow table that's part of an X-ray machine called a CT scanner. A soft, small tube will be placed into your rectum. This will fill your colon and rectum with air. The table will slide into the CT scanner. A series of X-rays will be taken. A computer will combine these to create a 3-D image. Because the test uses X-rays, it exposes you to a small amount of radiation. This test can be done without sedation. If polyps or any other changes are seen, you'll need a colonoscopy. This is done so the tissue can be removed for testing.

Blood tests

Blood tests can look for signs of colorectal cancer or polyps that may turn into cancer. A sample of your blood is taken in a clinic. It's tested in a lab. These tests are approved by the FDA for people at average risk who won't or can't use other screening tests. You don't need to do any bowel prep before this test. If you have abnormal results, you will likely need a colonoscopy.

Talking with your doctor

Talk with your doctor about which screening tests might be best for you. Each test has pros and cons. But no matter which test you have, the most important thing is that you get screened. If cancer is found at an early stage during screening, it's easier to treat. And treatment is more likely to work well. Cancer can even be prevented with routine screening tests.

If you have an abnormal test result from a screening test that's not a colonoscopy, you'll need to get one. It won't be thought of as a screening colonoscopy. So your deductible and co-pay may apply. Check with your health insurer so you know what to expect.

Ask your doctor about your level of risk. You may need to be screened on a different schedule if you are at higher risk of this cancer. Talk with your doctor about your health history to decide on the screening plan that's best for you.