Colorectal Cancer: What You Need to Know
Just the facts
Most colorectal cancers start as non-cancerous growths in the lining of the colon – these are called adenomatous polyps. Over time these polyps become larger and more can develop. Eventually some of the cells in the polyps may become cancerous. For that reason it’s important to know if you have polyps, and to remove them before cancer develops. Approximately 20% of patients 50 years old without a family history of colorectal cancer or any symptoms will have a polyp detected at screening.
Colorectal is the 2nd leading cause of cancer death in Canada (after lung cancer). It is slightly more common in men; they have a 1 in 14 chance of developing colorectal cancer during their lifetime (for women it’s 1 in 15). Colorectal cancer is highly treatable and usually curable if caught at an early stage. Unfortunately, almost 50% of people are diagnosed at a more advanced stage.
Risk Factors for Colorectal Cancer
Keep in mind that some younger people and some people with no risk factors develop colorectal cancer too. However, here are the main risk factors:
- Age: Risk increases after age 50
- Family history of colorectal cancer
- Polyps (non-cancerous growths) in the colon or rectum
- Poor lifestyle choices: a diet high in processed foods and low in fruits and vegetables, smoking, not exercising, drinking too much alcohol
- History of inflammatory bowel disease, such as Ulcerative Colitis or Crohn’s Disease
Symptoms of Colorectal Cancer
There are often no symptoms in the early stages of colorectal cancer – that’s why screening tests are so important. If you have symptoms get yourself to a doctor as soon as possible.
- Change in bowel movements
- Blood in the stools
- Narrower than usual stools
- Abdominal cramps or discomfort
- Unexplained weight loss or loss of appetite
- Sense of fullness or feeling that the bowel is not emptying completely
- Nausea & vomiting
- Gas & bloating
- Unexplained fatigue
Screening for Colorectal Cancer
The Colorectal Cancer Association of Canada recommends screening for all adults starting at age 50. However, those with additional risk factors should talk to their doctors about starting screening at an earlier age and/or being screened more often.
The most common screening test is called a fecal occult blood test (FOBT). It tests for blood in the stool that you can’t see with the naked eye. For the test you take a stool sample from 2 or 3 separate bowel movements and send them to a lab to be analyzed. If your test result is positive for blood you will be sent for more tests to find out the cause of the bleeding. Bleeding can have many causes, including ulcers, hemorrhoids, polyps, and cancer. Some of the other tests used to detect colorectal cancer are:
- Colonoscopy: A procedure that lets your doctor look at the lining of the entire colon, beyond the rectum and lower colon. A colonoscope is a flexible, lighted tube (endoscope) inserted through the rectum. If your doctor sees something abnormal, tissue samples (called a biopsy) may be taken during a colonoscopy. Polyps can also be removed during this test. Colonoscopy is the most accurate test for preventing and detecting colorectal cancer.
- Flexible sigmoidoscopy: A procedure that lets your doctor look at the lining of the rectum and the lower part of the colon, take biopsies and remove polyps. A flexible sigmoidoscope is a soft, bendable tube inserted into the rectum and lower colon.
- Double-contrast barium enema: An x-ray of the large intestine, filled with a barium solution, to check for polyps.
- Digital rectal examination (DRE): Your doctor inserts a gloved finger into the rectum to feel for abnormalities.
Average-risk people aged 50 and over should be screened using the fecal occult blood test (FOBT) at least once every 2 years. A colonoscopy every 10 years may be recommended.
People at high risk of developing colorectal cancer should be screened with colonoscopy and may need earlier and more frequent testing.
Talk to your family doctor about screening for colorectal cancer. To get a colonoscopy you will need a referral to a gastroenterologist. Colonoscopies usually take place in a clinic or hospital.
Getting screened could save your life. As they say, “don’t die of embarrassment”.