Screening Options

Colorectal cancer screening saves lives in two important ways:

• By finding and removing precancerous polyps before they become cancerous
• By detecting the cancer early when it is most treatable

All men and women over the age of 50 should be routinely screened for colorectal cancer. People with a high risk for CRC and those with family history should talk with their gastroenterologist about being screened at an earlier age.

Screening Tests
Screening is done on individuals who do not necessarily have any signs or symptoms that may indicate cancer. If symptoms exist, then diagnostic workups are done rather than screening. These are the tests available in screening for colorectal cancer and some general pros and cons for each:

Stool blood test (fecal occult blood test--FOBT)
Flexible sigmoidoscopy (flex-sig)
Colonoscopy
Barium enema with air contrast
Virtual colonoscopy (CT Colonography)

Stool blood test (fecal occult blood test--FOBT)
This test is used to find small amounts of hidden (occult) blood in the stool. A sample of stool is tested for traces of blood. People having this test will receive a kit with instructions that explain how to take stool samples at home. The kit is then sent to a lab for testing. If the test is positive, further tests will be done to pinpoint the exact cause of the bleeding.

A newer kind of stool blood test is known as FIT (fecal immunochemical test). It is very much like the FOBT but is perhaps a little easier to do and it gives a fewer number of false positive results.

PROS

• Simple
• Cost-effective
• Can be done in the doctor's office as a quick test but full test must be done at home

CONS

• Viewed as unsanitary by some
• Patient must retrieve samples form stool in toilet bowl
• DOES NOT DETECT CANCER, only detects blood presence in stool

Flexible sigmoidoscopy (flex-sig)
A sigmoidoscope is a slender, lighted tube about the thickness of a finger. It is placed into the lower part of the colon through the rectum. This allows the gastroenterologist to look at the inside of the rectum and part of the colon for cancer or polyps. Because the tube is only about 2 feet long, the doctor is only able to see about half of the colon. The test can be uncomfortable but it should not be painful. Before the test, you will need to take an enema to clean out the lower colon.

PROS

• cost effective than the more thorough and complete tests

CONS

• Can only examine the lower third of the colon
• Research has repeatedly demonstrated that in actual practice this test is not being used to its full effectiveness and therefore is rarely examining the entire third of the colon that it could view
• If positive diagnosis of polyps is found, MUST BE FOLLOWED UP WITH A COLONOSCOPY

Colonoscopy
A colonoscope is a longer version of the sigmoidoscope. It allows the doctor to see the entire colon. If a polyp is found, the gastroenterologist may remove it. If anything else looks abnormal, a biopsy might be done. To do this, a small piece of tissue is taken out through the colonoscope. The tissue is sent to the lab to see if cancer cells are present. This test can be uncomfortable, but not painful. Patients are given medicine through a vein to make them feel relaxed and sleepy. View an animation of this procedure.

PROS

• Examines the entire colon, making this the most thorough method for evaluating the colorectal area
• High detection rate for polyps, and ability to remove them immediately during the procedure, rather than scheduling a second exam
• Biopsies can be taken of any abnormal areas at the same time as the screening or diagnostic test is being done
• Given the "Gold Standard" rating above all other screening options by: American Society for Gastrointestinal Endoscopy (ASGE), American Gastroenterological Association (AGA), American College of Gastroenterology (ACG), and the American Cancer Society (ACS)

CONS

• More expensive than other types of screening if not covered by insurance

Barium enema with air contrast
A chalky substance is used to partly fill and open up the colon. Air is then pumped in to cause the colon to expand. This allows good x-ray films to be taken. Laxatives must be used the night before the exam and an enema is given the morning of the exam.

PROS

Lower cost than colonoscopy if neither is covered by insurance

CONS

Radiation has health risks associated with it

In practice, it is frequently not used effectively

Misses too many polyps

If positive diagnosis for polyps is found, MUST BE FOLLOWED UP WITH A COLONOSCOPY

Virtual colonoscopy (CT Colonography)
You might think of this as a super x-ray of the colon. Air is pumped into the colon to cause it to expand, and then a special CT scan is done. This test is not among those recommended by ASGE or the ACS for finding colon cancer early. More studies are needed to find out if it is as good as other existing methods of finding colon cancer early.

PROS

• Examines the entire colon
• High detection rate for polyps

CONS

• More expensive than other types of screening
• Cannot remove polyps
• Cannot take a biopsy
• If polyps or anything abnormal is found, MUST BE FOLLOWED UP WITH A COLONOSCOPY