Colorectal Cancer Screening: FOBT versus Colonoscopy

Dr. William Harris
Dr. William Harris, Regional Colorectal Screening/GI Endoscopy Lead and Surgeon, TBRHSC

It is estimated that 8,100 Ontarians are diagnosed with colorectal cancer each year and 3,300 will die from the disease, making it the second leading cause of cancer deaths in Ontario.

The good news is that there is something we can do to help identify cancers early, when they are easier to treat: cancer screening. When it comes to colon cancer, it is possible to identify the early signs of cancer and treat it before it becomes more serious. For example, we can intervene by removing potentially cancerous growths (polyps) in the colon and rectum, before they become cancer. For this reason, screening for colorectal cancer is especially important.

Cancer Care Ontario recommends that all adults between the ages of 50 to 74 years, with no family history of colorectal cancer, should be screened every two years using a simple take-home test called a Fecal Occult Blood Test (FOBT) kit. These kits are widely available from health care provider offices across the region or from your pharmacist or Telehealth Ontario for those without a primary care provider.

The FOBT tests for minute traces of blood in the stool, which may be a sign of colorectal cancer. Polyps or tumours in the colon have blood vessels on their surface which can release a small amount of blood into the stool allowing the test to help identify pre-cancerous growths early, before they become cancerous.  Stool samples are taken at three different times within a 10 day period and once completed, the kit can be mailed in a pre-addressed postage-paid envelope for laboratory analysis. The benefit of the FOBT is that it can be completed at home without requiring any time away from work or activities.

For people who have a first-degree relative (i.e. parent, sibling or child) with a history of colon cancer, the risk of developing the disease is even higher. For these people, a colonoscopy is recommended beginning at age 50, or 10 years earlier than the age at which their relative was diagnosed, whichever occurs first. For example, if you had a parent who was diagnosed at age 55, then you would go for your first colonoscopy at age 45. A colonoscopy examines the colon using a flexible tube with a tiny camera on the end.  It is relatively safe, only takes half an hour, and medication can be used to make the person feel comfortable.

Though there has been much debate in the media about using colonoscopy as the screening tool for colorectal cancer, colonoscopy is not standard for average risk patients for many reasons. The biggest impacts to the individual being the required liquid diet and procedure preparations, missing 1-2 days of work and the need for an escort to and from the appointment due to the use of sedation. A colonoscopy also comes with risks, as any surgery does, such as bowel perforation; and a much longer wait time in comparison to completing the FOBT kit at home.

All that being said, it is always important to remember that there is still much to be learned. As knowledge and technologies evolve, the techniques to prevent and screen for cancer will continue to evolve. As a doctor, surgeon (and a potential patient), I am excited to see what the future has to bring.