Colorectal Cancer Screening

What is colorectal cancer screening?

Colorectal cancer screening involves several tests or exams used to check for cancer of the rectum and colon (large intestine).

Why is colorectal cancer screening important?

Colorectal cancer is the second leading cause of cancer deaths in the U.S. It is often found too late for a cure. This does not always have to be the case. When found in the early stages, colorectal cancer can usually be cured by surgery. It is important for you to know the symptoms of colorectal cancer and to have the screening tests that can detect this cancer in its early stages before it causes symptoms.

If you have a parent or a sibling who has had polyps or cancer in the colon, you may be at an increased risk for polyps or cancer. (Polyps are growths inside the bowel that sometimes become cancerous.) With this family history, your health care provider may want to screen you for colorectal cancer at an earlier age and more often than people with no family history of these problems. When polyps are found, they can be removed before they become cancerous.

What are the signs of colorectal cancer?

Call your health care provider right away if you notice any of these signs of possible colorectal cancer:

rectal bleeding, which might show up as blood on toilet paper, in the toilet bowl, or in bowel movements
a change in your bowel movements, especially if you have bouts of constipation that alternate with bouts of diarrhea
pain in your lower abdomen that doesn't go away or that comes back often
a feeling of discomfort or the urge to move your bowels when there is no stool present.

What are the screening tests?

Four ways to screen for colorectal cancer are:

A digital rectal exam, in which your health care provider feels the inside of your rectum with a gloved finger to look for growths. This exam has limited value because your provider can check only the rectum and not the colon. Most colorectal cancers are in the colon.
A lab test of a sample of bowel movement (stool) for traces of blood. This test is relatively easy and inexpensive. However, many factors can interfere with its accuracy. Also, blood can be present for reasons other than colorectal cancer. Tests that show traces of blood need to be followed by more tests.

Eating certain foods before this test may lead to inaccurate results. For 2 days before having your stool tested, avoid eating turnips, horseradish, and red meat. Also, do not take vitamin C, iron supplements, or anti-inflammatory medicines, such as ibuprofen or aspirin, for 2 to 3 days before your test. If you have been taking these medicines daily, ask your provider if you should stop them for a few days before your test. Never stop your medicines without first asking your provider.
Flexible sigmoidoscopy. The doctor inserts a slim, flexible, lighted tube called a sigmoidoscope into your rectum. The doctor looks at the lower part of your colon with the scope. He or she can also use this tool to get samples of tissue for lab tests. About half of all colorectal cancers or polyps can be seen with this exam.
Colonoscopy. After giving you a sedative to relax you, the doctor inserts a slim, flexible, lighted tube called a colonoscope into your rectum. This tool is longer than the sigmoidoscope. With it the doctor can see most of the colon and check for polyps and cancer.

If a sigmoidoscopy or colonoscopy finds an abnormal area in the rectum or colon, the doctor can use the scope to remove a sample of tissue from the area for lab tests (a biopsy). Sometimes the entire abnormal area can be removed with the scope. If an abnormal area is too large to take out with the scope and it needs to be removed, surgery will be needed.

When should I have screening tests for colorectal cancer?

Doctors don't all agree on the best timing for colorectal screening. There is also controversy over which procedures are best. Ask your health care provider what tests are best for you and when you should have them.

If you are age 40 or over, ask your health care provider if you should have the digital rectal exam and how often.

If you are over age 50, ask your health care provider how often you should have a stool sample tested for blood and a sigmoidoscopy or colonoscopy. If you are at risk for developing colorectal cancer (for example, you have a family history of colon polyps or cancer), your provider may recommend these exams at an earlier age.

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File TST5112F.HTM Release 9.0/2006