Everybody poops.

Your colon is where the action happens. Everything you eat eventually works its way through 60 inches of colon and voila! — poop. While most people are more preoccupied with what comes out in the end, it’s worth taking the time to think twice about what’s going on in those dark twisty colon corners and how you can keep it healthy.
Colon cancer is the third most commonly diagnosed cancer in Canada and, on average, 69 Canadians are diagnosed with colon cancer every day.

How does colon cancer develop?
Most colon cancers are thought to arise from colon polyps, which are growths that form along the inner lining of the colon. As the polyps grow, they accumulate mutations that eventually transform the benign growths into cancer. The most common type of colon cancer is called adenocarcinoma.
Because colonic polyps are usually asymptomatic, which means there is no symptoms, screening is needed to identify and remove them before they have a chance to become cancerous. By doing so, we can reduce the incidence of colon cancer. While not every single polyp will eventually become a cancer, we have no way of knowing which ones will or won’t, so the recommendation is to remove them once they’ve been found.

What’s the likelihood I’ll get colon cancer?
In Canada, one in 14 men are expected to develop colorectal cancer during his lifetime, and one in 29 will die of it.1 Most people — 75 percent— who develop colorectal cancer have no risk factors, so it’s important even if you’re fit and healthy to undergo screening. Certain factors will increase that risk, which has implications for how early and often you should be screened.

  • Family history of colon cancer – The next time you’re at a family gathering, here’s a topic for the dinner table. You’re twice as likely to develop colon cancer if a first-degree relative (mother, father, sibling) has been diagnosed with it. If you have two or more first-degree relatives diagnosed with colon cancer, your risk is quadrupled. Depending on how old the relatives were at the age of diagnosis (younger than 50), you may need to be screened starting at an earlier age compared to people who do not have a family history.
  • Inflammatory bowel disease – Diseases like ulcerative colitis and Crohn’s disease that cause chronic inflammation of the colon lining increases the likelihood of cancers forming. If you’ve been diagnosed with inflammatory bowel disease, make sure you talk to your doctor about the proper screening regimen to detect any changes early.
  • Hereditary colon cancer – Some families are at high risk of colon cancer due to hereditary genetic syndromes or a particularly strong family history. If multiple people in your family have been diagnosed with colon polyps or cancers of the colon, small bowel, or endometrium (uterine lining), there may be a hereditary cause. It’s important to talk to your doctor because you may benefit from early, intense surveillance, genetic testing, or even prophylactic surgery if you have genes that predispose you to cancers.

Is there anything I can do to prevent colon cancer?

  • Diet and lifestyle – Some research suggests that maintaining a healthy weight, eating a high-fibre diet rich in fruits and vegetables, eating less meat, not smoking, limiting alcohol consumption and regular exercise may reduce your risk of colon cancer. The direct link between eating more plants and reducing colon cancer risk is inconsistent. That doesn’t mean that you should let healthy choices fall to the wayside; a healthy lifestyle lowers your risk of heart disease, diabetes and other things you want to avoid.
  • Get screened! Screening helps detect polyps and cancers early so they can be more easily treated. Screening applies to people who are aged 50-74 who are asymptomatic and don’t have risk factors. If you fall into this category, make sure you talk to your doctor at your next checkup to arrange screening tests.

What should I look out for? What are the warning signs?

  • Most colon cancers are asymptomatic – This is why it’s important to get screened even if you don’t have symptoms.
  • Look at your poop – Sounds weird but many people flush and never take a moment to admire their brown masterpiece. After that morning coffee, take a look in the toilet so you know if there is blood or changes in diameter. What you see may surprise you.
    – Bleeding – Whether it’s in the toilet bowl or on the toilet paper, any new bleeding should prompt a discussion with your doctor at your next visit. Before you panic, keep in mind that most bleeding out the bottom end is not because of cancer. However, the only way to be certain that new bleeding symptoms aren’t due to a new polyp or cancer is to get a scope test to take a look. Keep your doctor in the loop and don’t hesitate to ask for a scope referral.
    – Change in bowel habit – If you notice your stool becoming pencil-thin or if you are constipated, this could be a sign that something is causing a blockage or narrowing.
  • If you have symptoms, talk to your doctor about referring you to a gastroenterologist or general surgeon for colonoscopy.
  • Any new or concerning symptoms should prompt a visit to your doctor to discuss whether a colonoscopy would be needed even if you have had negative screening tests in the past.

What are the different types of screening tests? How often do I need to do them?

There are different options for screening that are recommended by the Canadian Association of Gastroenterology., Depending on where you live and what’s available, you may be offered different options. Most people who are getting screened will have normal results. However, if a screening test comes back positive, you’ll need a full colonoscopy to confirm.

  • Fecal occult blood testing (FOBT) – Every two years
    – Yes, you heard right – poop tests. Colon tumors can bleed microscopic amounts that might not be seen with the naked eye and stool testing is a relatively hassle-free (though potentially a little messy) way of detecting it. You can pick up a card from your family doctor or have it mailed to your home. Once you’ve had a chance to provide a sample, the poop-card gets mailed off for analysis and the results are sent to your doctor. If blood is detected, the results are abnormal and you need a full colonoscopy to take a look. Most people who have blood in their stool don’t have colon cancer and might have another source of bleeding such as hemorrhoids. A positive test merits a look with a scope just in case. A negative test is normal and you’ll have to repeat the test every two years.
    – There are two commonly used stool tests:
    The chemical guaiac is used to detect the iron containing component of blood in the stool
    Note that some foods (iron supplements, red meat) can cause false positives, so follow the instructions carefully.
    Fecal immunochemical test (FIT)
    This test uses antibodies to detect human blood proteins in the stool. It can be easier to use because there are no food restrictions so you are less likely to get a false positive.
    If FIT testing is available in your region, it is preferable over the guaiac test.
  • Flexible sigmoidoscopy – Every 10 years
    – You can consider this the abbreviated version of a colonoscopy. Since most colon cancers develop in the left or “downstream” colon, a flexible sigmoidoscopy takes a look where the money is most likely to be. The benefit is that since the scope doesn’t have to turn all the deep dark corners of your colon, this is a quick procedure that can usually be done without sedation in five minutes. If polyps are found on the sigmoidoscopy you’ll need a colonoscopy to make sure there aren’t any polyps hiding upstream, because the presence of one polyp anywhere in the colon increases the likelihood there is a second polyp elsewhere. Flexible sigmoidoscopy can also be combined with fecal testing.

What if my screening test comes back positive? 

If you have any risk factors or symptoms, or if any of your screening tests come back positive, you get on the express train to a full colonoscopy. This is considered the best test for finding a cancer or a pre-cancerous polyp. Your family doctor will need to refer you to a gastroenterologist or a general surgeon for the procedure. This is typically a same-day (meaning you go home afterwards) procedure done with or without sedation, and requires a full “colon prep” with laxatives the night before so the best view can be obtained.
A special flexible scope is used to take a high-definition view of the colonic lining. Any polyps that are found can be removed right then and there via a polypectomy before they have a chance to grow into a cancer. Sometimes small cancers can even be treated successfully with just colonoscopy and polypectomy. If a gnarly looking, possibly cancerous, polyp is found, the endoscopist can take biopsies to confirm the diagnosis and mark the site with special ink in case surgery is needed.
Depending on the type, number and size of polyps found, you may need a repeat colonoscopy in three, five or 10 years to keep any new polyps in check. The bowel preparation, which consists of a night of drinking laxatives, isn’t the most pleasant but if you’re average risk and have a normal colonoscopy, you won’t need re-testing for another 10 years.

What if cancer if found?
Colon cancer is highly treatable, especially if detected early. Surgery can be curative for early stage tumors, which is why your physician wants to find any cancers before they have a chance to spread outside of the colon.

The bottom line
Get behind your behind! Talk to your doctor about when is the right time to start screening and don’t bail on that colonoscopy appointment.


  1. Canadian Cancer Society Statistics publication
  2. Winawer SJ, Zauber AG, Ho MN et al. Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. N Engl J Med. 1993 Dec 30;329(27):1977-81.
  3. Butterworth AS, Higgins JP, Pharoah P. Relative and absolute risk of colorectal cancer for individuals with a family history: a meta-analysis. Eur J Cancer. 2006 Jan;42(2):216-27. Epub 2005 Dec 9.
  4. Aleksandrova K, Pischon T, Jenab M et al. Combined impact of healthy lifestyle factors on colorectal cancer: a large European cohort study. BMC Med. 2014 Oct 10;12:168. doi: 10.1186/s12916-014-0168-4.
  5. Leddin DJ, Enns R, Hilsden R et al. Canadian Association of Gastroenterology position statement on screening individuals at average risk for developing colorectal cancer: 2010. Can J Gastroenterol. 2010 Dec; 24(12): 705–714
  6. Leddin D, Hunt R, Champion M et al. Canadian Association of Gastroenterology and the Canadian Digestive Health Foundation: Guidelines on colon cancer screening. Can J Gastroenterol 2004 Feb 2(18): 93-99.