What is Colorectal Cancer?

Colorectal cancer (CRC) is the second leading cause of cancer mortality in North America, next to lung cancer. An estimated 6% of Canadians will develop CRC, half of whom will be asymptomatic until advanced stages of the disease emerge. CRC generally develops from benign adenomas, called polyps, which physicians can easily detect and remove during colonoscopy. It could take a polyp ten to fifteen years to develop into cancer. Screening for polyps and removing them during a colonoscopy can dramatically improve patient health outcomes, because when detected in its early stages, colorectal cancer is easily treated. Physicians diagnose close to 19,200 patients with CRC each year in Canada, and 8,400 will die from the disease.

Unfortunately, only 1 in 5 Canadians undergo the important screening process. The prospect of colonoscopy may be daunting to patients who recall “horror stories” of painful colonoscopies from a previous era, when equipment was larger and less flexible, and some are simply too embarrassed to think or talk about bowel related issues. Thankfully, modern technology has made colonoscopy a vastly more comfortable procedure to undergo, and it is now more socially acceptable to discuss medical issues such as bowel habits than in the past.

How is CRC detected?

Screening is a term that describes when doctors perform regular tests or examinations in people who do not have any signs of a disease. These individuals may be more likely to develop a disease because they have high risk factors. There is much debate over the extent to which screening of the general population for polyps or CRC needs to take place, and by what means.

In Canada, there are a number of screening tools available for your doctor to use to determine if you are progressing toward CRC. Researchers continue to find ways of detecting and predicting CRC that include studying a patient’s DNA for known genetic markers that place them at a higher risk of developing CRC. Some of the more common current tests are shown below along with the recommended interval for these tests to occur (shown in brackets) for all individuals over age 50 with no family history of CRC. Those with higher risk factors require screening that is more frequent.

Colonoscopy
During this procedure, a doctor inserts a thin flexible tube with a tiny camera into the colon through the rectum. The procedure usually takes place in an outpatient clinic, often located within a hospital. As with the sigmoidoscopy, while viewing the surface of the lining of the entire colon, the physician may take a small amount of tissue (biopsy) of specific areas that will later be examined in a laboratory or they may remove entire polyps on the spot. Light sedation makes the procedure more comfortable for the patient. (Every ten years)

Which Test Is For Me?

Of these common tests, colonoscopy is the most accurate means of detecting polyps or CRC and allows for the immediate removal of most polyps. Patients may choose to watch on a video screen. The procedure usually takes ten to twenty minutes. Recovery is quick and usually pain-free.

For IBD patients and others at high risk, a colonoscopy provides the greatest reassurance that his or her colon is free of cancer. Other tests to screen for CRC are less reliable but may be acceptable for those not considered to be at high risk. The intervals for the screening tests mentioned above are more frequent when there is greater risk. Your doctor will determine the appropriate interval for you.

Our American neighbours are encouraged by health policy makers to undergo colonoscopy regardless of their individual likelihood of developing CRC, but Canadian policy toward average risk patients is ambivalent, probably because we lack the capacity to perform the requisite number of colonoscopies. However, for individuals who have an above average risk of developing CRC, doctors recommend colonoscopy screening. Of course, individuals who notice blood in their stools or who have other bowel related symptoms should immediately report these to their physician.

Who Should Be Screened?

The Canadian Association of Gastroenterology and the Canadian Digestive Health Foundation Guidelines on Colon Cancer Screening recommend that:

  • People with chronic IBD (colonic Crohn’s disease or ulcerative colitis) should be screened every 1 to 2 years, once they have had the disease for 8 to 10 years.
  • Those with a first-degree relative with CRC (parent or sibling) diagnosed before age 60, or with multiple affected relatives, should be screened once every 5 years. The first screening should take place 10 years
  • Before the relative’s age of diagnosis or at age 40, whichever comes first.
  • Individuals with three or more affected relatives, or with a first degree relative affected before age 40, should be considered for genetic counselling and possibly genetic testing for specific hereditary diseases which dramatically increase the CRC risk and which may require much more intensive screening.
  • People with no risk factors should be considered for some form of screening beginning at age 50; this may be colonoscopy every 10 years, fecal occult blood testing every 1-2 years, or other options that may be discussed with their physician.
  • Remember, colonoscopy in expert hands is generally not painful. In fact, most patients report that the most unpleasant part of the procedure is the preparation. However, while it is true that the side effects of some preparation medications can be unpleasant, a newer product available might suit your tastes better.