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.
Background
Although the number of people affected with CRC is declining, it is still the third most common form of cancer, after breast and lung cancer in women, and prostate and lung cancer in men. Approximately 17,600 new cases will be diagnosed in Canada this year, with approximately 6,500 Canadians dying from CRC.
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 of CRC. However, there are risks (and other benefits) associated with the routine use of NSAIDS.
How the Government is Taking Action on Colorectal Cancer
Health Canada is involved in the work by 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.
Health Canada has recently prepared a report on the impact of screening Canadians for CRC. This report highlights the evidence surrounding screening, including the expected benefits, risks, and needed resources.
Need More Info?
For more information, contact:
Screening and Early Detection Section
Chronic Disease Prevention Division
Centre for Chronic Disease Prevention and Control
T. Tofano/J. Beaulac tel: (613) 946-9967
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