Should You Be Tested for Colorectal Cancer?

One-Third Of People At Risk For Colon Cancer Aren't Getting Screened

Polyp Removal
The best way to prevent colon cancer is to have a colonoscopy and get any polyps removed.. Image © SEBASTIAN KAULITZKI / Getty Images

Colorectal cancer, the second leading cause of death from cancer in the United States, will cause about 50,000 deaths in the U.S. every year. Specialists recommend that everyone over the age of 50 be screened for colon cancer. Despite the high numbers of diagnosis and deaths from colon cancer,, only two-thirds of Americans over the age of 50 have been screened. The good news is that, when caught in its early stages, colorectal cancer is approximately 90% curable.

So, who should get screened for colorectal cancer?

Why Screen?

The purpose of screening for colorectal cancer is to find any abnormal growths in the colon called polyps. Polyps grow on the intestinal wall, and are the precursor to cancer. If found during a colonoscopy or a sigmoidoscopy, polyps can be removed with an attachment that is on the end of the colonoscope. If the polyp is found and removed during screening, it can not turn into cancer.

Who To Screen?

If you are over the age of 50, the American Gastroenterological Society recommends that you be screened for colorectal cancer. Several options for screening are available, and the method best for each individual patient should be discussed with a physician. Not every method will work for every patient: the doctor and patient should come to an agreement about the best method to use.

People under the age of 50 who have a family history of colorectal cancer, inflammatory bowel disease (IBD), a personal history of cancerous growths or adenomatous polyps, or hereditary syndromes such as familial adenomatous polyposis (FAP), should also be screened for colorectal cancer on their physician's recommended schedule.

It is critical that people who are in one of these high-risk categories talk to a doctor about the best time to start screening, which test to use, and how often testing is needed. For people at high-risk of developing colorectal cancer, screening may be needed earlier and more often than for people at average risk (which is generally defined as people who are over the age of 50).

Why a Colonoscopy Is Best

There are several types of tests available, but the colonoscopy is the gold standard. The reason why is that a colonoscopy can be used to screen the entire colon for polyps, and then remove them. Other tests have some drawbacks. A flexible sigmoidoscopy will only test part of the colon: any polyps that go beyond the scope range will be missed. A barium enema is a type of x-ray and offers no ability to remove polyps. If polyps are detected during this test, a colonoscopy will be recommended anyway. A stool test will find blood in the stool, but by the time a polyp is present and bleeding, it could also be cancerous. If blood is found in the stool, a follow-up colonoscopy may be recommended anyway. 

The upshot is that having a colonoscopy is going to offer the best chance of finding and removing polyps before they can turn cancerous. If another test is used and a polyp is seen or suspected, a colonoscopy is going to be recommended anyway. 

Other Colon Cancer Screening Methods

Stool Test. If a fecal occult blood test (FOBT) is used as the screening method, it's recommended that this test be repeated every year.

A FOBT is used to examine the stool for traces of blood that cannot be seen with the naked eye. This test can be taken at home and may detect bleeding from almost anywhere in the digestive tract, including that which is coming from polyps.

Sigmoidoscopy. In addition to the yearly FOBT, a flexible sigmoidoscopy is recommended every 5 years. A sigmoidoscopy is a way for a doctor to examine the last one third of the large intestine, which includes the rectum and the sigmoid colon. A flexible viewing tube with a lens and light source on the end, called a sigmoidoscope, is used. Looking through the eyepiece at the other end of the scope, the doctor can see the inside of the colon. In this test, the doctor can check for cancer, polyps, and ulcers.

Barium Enema. One alternative to the flexible sigmoidoscopy is the double-contrast barium enema. A barium enema (also called a lower gastrointestinal series) is a special type of x-ray that uses barium sulfate and air to outline the lining of the rectum and colon. A barium enema can be performed as an outpatient procedure and usually takes about 45 minutes. The enema might be uncomfortable, but the x-rays are completely painless. This test is also recommended every 5 years for those using this screening method.

Colonoscopy. A colonoscopy is recommended once every ten years, or as a follow-up if any blood, polyps or abnormalities are found during any of the tests above. During a colonoscopy, a physician can examine the inside of the colon beyond the areas a sigmoidoscopy can reach. The colonoscopy procedure can take up to 1 1/2 hours and is performed under sedation in a hospital as an outpatient procedure. An attachment at the end of the colonoscope may be used to take a biopsy of the tissue in the colon. If a polyp is found, it may be removed and both biopsies and polyps will be sent to a laboratory for further testing.

Colon Cancer Screening Guidelines for People Over Age 50

Regular screening should include one of the following options:

  • FOBT every year
  • Sigmoidoscopy every 5 years
  • FOBT and sigmoidoscopy every 5 years
  • Double-contrast barium enema every 5 years
  • Colonoscopy every 10 years

Sources:

American Cancer Society. "What are the key statistics about colorectal cancer?" 31 Jan 2014. 28 Feb 2014.

Centers For Disease Control And Prevention. "Colorectal Cancer Tests Save Lives." Vital Signs. 2013. 28 Feb 2014.

Continue Reading