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Your Questions — 6 minutes

Fecal blood testing and colorectal cancer

Does a positive fecal blood test result necessarily mean that a person has colon cancer?

False. Several other conditions can lead to traces of blood in the stools: hemorrhoids, anal fissures, constipation or inflammatory bowel disease can also give negative test results. It is estimated that there is a one-in-four (25%) chance that a large polyp or adenoma is responsible for the bleeding and a one-in-forty (2.5%) chance that the bleeding is due to cancer.

Does a negative fecal blood test result eliminate the possibility that colon cancer is present?

False. Polyps and tumours do not continuously discharge blood. It is possible that a lesion did not bleed on the day you collected your sample. For this reason, the test should be repeated at least every two years (MSSS program) or ideally every year (U.S. recommendations). Some Canadian provinces even request the collection of two samples to increase cancer detection.

Is fecal blood testing used for diagnosis?

False. Fecal blood testing is used for screening. Only an optical or virtual colonoscopy is able to diagnose the presence of a polyp, adenoma or cancerous lesion.

Is a virtual colonoscopy (radiological exam) as effective as an optical colonoscopy (insertion of a tube into the anus) for diagnosing the presence of colorectal cancer?

True. The two approaches perform similarly well. However, only an optical colonoscopy allows the removal of any lesion considered suspicious at the same time. Polyps and adenomas cannot be removed with a virtual colonoscopy, but it does enable the diagnosis of other lesions in the abdomen which are not visible with an optical colonoscopy (e.g. ovarian cyst).

Isn’t colorectal cancer essentially a disease that affects the elderly?

False. Although colorectal cancer is most often diagnosed in people over the age of 60, the incidence of colorectal cancer in people under age 50 appears to be steadily increasing in North America. Currently, about 15% of colorectal cancers are diagnosed in people under 50 years of age and these cancers are often more aggressive than those diagnosed in older individuals.

Is red meat responsible for colorectal cancer?

True. A major American study of 500,000 retirees showed that individuals who consumed the most red meat had a 30% higher risk of developing colorectal cancer than individuals who consumed the least. This also holds true for processed meats (e.g. bacon, sausage, deli meats), with a risk up to 20 times higher among large consumers of these products.

Isn’t colorectal cancer a disease that only affects men?

False. Cancer rates in men and women are very similar. One in fourteen men are at risk of developing this cancer in their lifetime, while the rate for women is one in fifteen.

Does eating fish protect you against developing colorectal cancer?

Maybe. Although eating fish is recommended for several other good reasons, the links between fish consumption and colorectal cancer are not well established. At the very least, adding fish to your diet allows you to reduce your intake of red and processed meats.

Isn’t it true that alcohol consumption in reasonable doses (i.e. no more than three glasses a day for men) is not associated with the development of colorectal cancer?

Uncertain! Although excessive alcohol consumption is definitely associated with a higher risk of colon cancer, there is no minimum dose below which the risk disappears completely.

Isn’t colorectal cancer an inherited disease that cannot be prevented?

False. Less than 10% of colorectal cancers are believed to be of genetic origin. The vast majority of cases are due to poor lifestyle habits. Many studies indicate that simple measures can significantly reduce the risk of developing colorectal cancer:

  • Be physically active.
  • Maintain a healthy weight.
  • Limit your consumption of red and processed meats.
  • Limit your alcohol consumption.
  • Choose foods rich in fibre.
  • Take regular fecal occult blood tests.

Do not hesitate to have a colonoscopy if your fecal blood test result is positive or if you are in a higher risk category (first-degree relative with colorectal cancer, etc.).

If you have any questions or need more information, please don’t hesitate to call our customer service number at 1 833 590-2715.