Colorectal cancer: Screening or diagnosis?

With more than 25,000 new cases and 9,500 deaths per year, colorectal cancer is the third most frequently diagnosed cancer in Canada. In Quebec, it is the second leading cause of cancer deaths in both men and women.

The screening test is based on the fact that large polyps, tumours (also called “adenomas”) and cancers discharge small amounts of blood into the intestine, which are then passed in the stool. These quantities are generally too small to be detected by the naked eye, hence the term “occult blood.” In Quebec, the recommended screening test is the fecal immunochemical test (FIT), also known as the immunochemical fecal occult blood test (iFOBT) [2].

In theory, the larger and more advanced a polyp, tumour or cancer, the greater the amount of blood in the stool. However, this is not always the case: the discharge of blood may be irregular, and even a good-sized tumour may not have bled sufficiently by the time stool samples are collected for the screening test to be positive.

1. Anyone with a prescription issued by a health care professional is eligible.
2. The test is also available without a prescription for people aged 50 to 74 without symptoms or particular risk factors, and from the age of 40 for those with a particular profile [2]. To determine your eligibility, please complete this short questionnaire.

Symptoms suggestive of colorectal cancer

• Recent and persistent changes in bowel habits, such as diarrhea, constipation or pain during bowel movements
• Visible blood in the stool, whether black or bright red
• Bleeding after bowel movements
• Documented, unexplained anemia

Special risks that justify going directly to a colonoscopy

• Personal or family history of colorectal cancer, polyps or chronic inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis.
• Family history of genetic diseases that increase the risk of colorectal cancer, such as Lynch syndrome or the various forms of familial adenomatous polyposis (FAP).

Restrictions on access to the Quebec program without a doctor’s prescription

• People over the age of 75
• People who have had a FIT in the last two years
• People who have had a virtual colonoscopy in the last five years
• People who have had an optical colonoscopy in the last ten years

Negative result: There is most likely no significant cancer, adenoma or polyps. A colonoscopy is not recommended. However, tumours do not bleed continuously, and a negative test does not entirely eliminate the possibility that a tumour or cancer is present. This is why the test should be repeated every two years.

Positive result: The fecal occult blood test is not a diagnostic test;: there may be blood in the stool for other reasons. A positive FIT result does not necessarily mean the presence of cancer, but it does indicate the need for a medical follow-up. Hemorrhoids, anal fissures, constipation or inflammatory bowel disease can also cause blood in the stool. In Quebec, out of every 1,000 people who take the screening test, between 30 and 40 will have blood in their stools. About half will show adenomas or large polyps during a colonoscopy, while about one in ten will have a developing cancer [3].

A colonoscopy is an examination that involves inserting a long tube called an endoscope into the rectum. The endoscope is fitted with a small camera and a tool for removing small fragments of tissue. The tube is advanced slowly into the colon, ideally to the junction between the large and small intestines, known as the cecum.

The small camera transmits real-time images of the intestinal wall to a video screen, allowing the specialist performing the examination (the colonoscopist) to detect the presence of suspicious tissue, such as polyps or adenomas. Thanks to the integrated tool, biopsies can be performed or polyps completely removed (polypectomy). An optical colonoscopy requires adequate preparation of the colon: it must be completely emptied, and the patient is sedated during the procedure.

A successful colonoscopy relies on good bowel preparation and complete visualization of the large intestine, right down to the cecum. A negative result means there is no evidence of cancer, and, therefore, no need to re-test for ten years. The patient is encouraged to repeat the FIT every two years [4]. A positive result, on the other hand, indicates the presence of cancer or “advanced” or “non-advanced” polyps. Depending on the number, appearance and size of the polyps, it will be necessary to either continue fecal immunochemical testing every two years (for small polyps) or schedule a new colonoscopy three to ten years later.

As with many other cancers, survival is very high when colorectal cancer is diagnosed at an early stage. If this cancer is diagnosed at stage 1 (i.e. when the abnormal cells are still in their tissue of origin), the survival rate is over 90% five years after the diagnosis. Simply testing for blood in the stool with a FIT, therefore, has the potential to save many lives. With the test now available without a doctor’s prescription, it is recommended that all those concerned take full advantage of it [5].

Are you concerned about colorectal cancer? Complete our short questionnaire to confirm your eligibility for the screening program and order your at-home collection kit.

Order a screening kit

Do you already have a medical prescription for this test? Schedule an appointment online or contact Biron Health Group’s customer service at 1-833-590-2712.