Screening for Colorectal Cancer

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The Issue

Colorectal cancer (CRC) is the third most common cancer in Canada. Regular screening can diagnose the disease at an early stage when it is more treatable, therefore reducing mortality.


Although the number of people affected with CRC is declining, it is still the second most common form of cancer in men and the third most common form of cancer, after breast and lung cancer in women. In 2007, an estimated 20,800 Canadians will be diagnosed with CRC and 8,700 will die of it. On average, 400 Canadians will be diagnosed with CRC and 167 will die of CRC every week.

CRC is a malignant tumour that develops over a period of time (at least 10 years) on the bowel wall, before invading the wall and moving on to other organs. Approximately two-thirds of these cancers are found in the large intestine and one-third in the rectum. CRC usually develops from benign tumours or polyps found in the bowel.

Symptoms of CRC depend on the lesion's location, type, extent and complications, and may include:

  • Fatigue and weakness
  • A change in bowel habit (alternating constipation and increased stool frequency)
  • Stool streaked or mixed with blood
  • Discomfort or pain in the lower abdomen

Symptomatic CRC is usually investigated by examining the stool for evidence of blood by using the Fecal Occult Blood Test (FOBT), by ultrasound, and/or by a digital rectal exam. If positive, further tests such as a colonoscopy are done.

Even if you are not experiencing any symptoms, CRC may be detected using the FOBT. The Canadian Task Force on Preventative Health Care recommends that if you are over 50 years of age, you should have an FOBT every one or two years. Studies show that regular FOBT testing may lower the mortality rate of CRC by 15 to 33 percent.

Risk Factors For Colorectal Cancer

  • Age: the older you are, the more likely you are to develop CRC. Most of those diagnosed are 70 years or older.
  • Heredity: you are more likely to get CRC if someone in your family, especially your immediate family, has been diagnosed with it.
  • Diet: a diet high in red meat and low in fruits and vegetables may increase your risk.
  • Weight: obesity and a lack of physical activity increase the risk.
  • Alcohol consumption: alcohol, especially beer, may increase your risk. Lower rates of CRC have been found in those who drink no alcohol.
  • Smoking: smoking also increases your risk.

Minimizing Your Risk

Discuss with your physician whether you should be screened. Your physician may recommend, based on your family history and any medical history, a FOBT test every year or two, with follow-ups on positive tests by colonoscopy. There are also changes that you can make in your lifestyle to reduce your risk of CRC:

  • Increase your intake of fruits and vegetables (especially those high in folate), and reduce your consumption of red meat.
  • Limit your intake of alcoholic beverages.
  • Exercise regularly. Participate in some form of physical activity, even a long brisk walk, at least three times a week.
  • If you are overweight, try to lose weight by combining healthy eating and more physical activity.
  • Quit smoking to lower your risk of CRC and other forms of cancer and heart disease.
  • Consult with your doctor about the possibility of taking non-steroidal anti-inflammatory drugs (NSAIDS) such as acetylsalicylic acid, which have been found to reduce the risk CRC. However, there are risks (and other benefits) associated with the routine use of NSAIDS.

Government of Canada's Role

Health Canada and the Public Health Agency of Canada are involved in work with the Canadian Task Force on Preventative Health Care, which assesses evidence surrounding the prevention of disease and provides regularly updated clinical practice guidelines for physicians.

The Centre for Chronic Disease Prevention and Control (CCDPC), within the Public Health Agency of Canada, works with stakeholders at all levels to provide pan-Canadian and international leadership in chronic disease prevention and control through integrated policy and program development, surveillance, and knowledge development and dissemination.

Need More Info?

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Updated: July 2007
Original: September 2002
©Her Majesty the Queen in Right of Canada, represented by the Minister of Health, 2007

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