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 US. 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 healthcare 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 early, they can be removed before they become cancerous.

What are the signs of colorectal cancer?

Call your healthcare 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?

Tests used to screen for colorectal cancer are:

• FOBT (fecal occult blood test) or FIT (fecal immunochemical test). This is a lab test of a sample of bowel movement (stool) for traces of blood. The test may be done in your healthcare provider's office. Or your provider may give you 3 test cards and ask you to collect tiny samples of stool at home on 3 different days. You will put the samples on the cards and return the cards to your provider's office. The samples will be tested to see if any blood is present.

  This test is relatively easy and does not cost much. However, many things can affect its accuracy. Also, blood may be in the stool samples for reasons other than cancer. When the FOBT finds blood in your stool, more specific tests need to be done to look for the cause.

  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.

  The FIT is the same procedure as the FOBT except a different chemical is used to test the stool samples. This chemical is more specific than the FOBT chemical. For the FIT you do not have to avoid some foods or medicines before you collect the stool samples.

• Flexible sigmoidoscopy. The doctor inserts a slim, flexible, lighted tube called a sigmoidoscope into your rectum. The doctor looks at your rectum and 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. Because this test looks just at the lower part of the bowel, only 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 or all 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. The removal of tissue is called 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.

• Virtual colonoscopy is a way to look at the colon and screen for cancer without putting a scope into the colon. It is a CT scan done with special techniques to look for polyps in the colon and rectum.
• Double-contrast barium enema. After an X-ray is taken to check that your intestines are free of stool, the a lubricated tube is inserted into your anus. Barium, which is a fluid that can be seen on X-rays, is passed through the tube into your rectum and colon. Air is also pumped into the colon to help the radiologist see any abnormal areas. The flow of barium in the colon can be seen with a fluoroscope, which is a special X-ray machine that uses continuous X-rays to show movement. Other names for this test are air contrast barium enema, lower gastrointestinal (GI) exam, and lower GI.

When should I have screening tests for colorectal cancer?

If you are 50 or older and have an average risk of colon cancer, it is generally recommended that you:

• Have your stool checked for blood (FOBT or FIT) once a year.
• Have your first sigmoidoscopy or colonoscopy at age 50.
• Have another sigmoidoscopy every 5 years or colonoscopy every 10 years.

If you have not recently had a colonoscopy and the results from any of the other tests are positive, then you will need to have a colonoscopy to make sure no cancer is present.

If you have a higher than normal risk for colorectal cancer, ask your healthcare provider when and how often you should be tested for colorectal cancer. You may need to start testing before you are 50.

You may have a higher risk of colorectal cancer if you have:

• a history of colon polyps or previous colorectal cancer
• a history of chronic inflammatory bowel disease, such as Crohn's disease
• an immediate relative with colorectal cancer
• a family history of colon cancer diagnosed before age 50
• a family history of an hereditary colorectal cancer syndrome.