March is colorectal cancer awareness month.
What is colorectal cancer?
Colorectal or colon cancer, which affects the last six feet of the small intestines and rectum, is one of the most common type of cancer in Canada. 
Overall, colorectal cancer is the second leading cause of death from cancer (men and women combined). On average, 413 Canadians will be diagnosed with colorectal cancer every week, and 171 Canadians will die of it. (source)
What is my risk?
Your risk increases dramatically as you get older: after age 30, your risk basically doubles every decade. Men and women are equally at risk for this disease. According to the Canadian Cancer Society, one in 14 men is expected to develop colorectal cancer during their lifetime and one in 27 will die of it. One in 16 women is expected to develop colorectal cancer during their lifetime and one in 31 will die of it. (source)
Doctors usually suggest regular screening tests beginning around age 50. These tests are important, because this type of cancer responds best to treatment if caught early.
A new online risk assessment tool offered by the US National Cancer Institute estimates the risk that a white man or woman who is 50 to 85 years old will develop colorectal cancer. It will soon be adapted for African-Americans, Hispanics and Asian-Americans. People using this tool should work with their health care providers to interpret the results.
Is it curable?
Doctors have identified different stages of cancer, based on the size and how much it has spread. Treatment is most effective when the cancer is localised (before it has spread too far). Cancer often spreads to other organs of the body through the lymphatic system — bean-shaped concentrations of immune cells (“lymph nodes”) scattered throughout the body and connected by a network of tubes. This is called “metastasis”. (source)
For colorectal cancer, the stages indicate how far the cancer has penetrated the wall of the intestine. Stage 0 is the earliest stage: the cancer has not grown beyond the inner layer (“mucosa”) of the colon or rectum. In stage I, there is some penetration, and more penetration in stage II. At stage III, the cancer has affected the lymphatic system. Stage IV indicates that the cancer has spread to other organs in the body ("metastasized").
Even after an apparently successful treatment the cancer may reappear, often in the liver or the lungs. This is called “recurrent cancer”.
No one really knows what causes cancer, Healthy Ontario. Cancer. (undated) but cancer risk is predicted by analysing cancer rates in the general population. Experts suggest that, like many cancers, colon cancer is partly genetic, partly environmental, and maybe even partly random.
What are the symptoms or warning signs?
Many intestinal cancers display no symptoms at all, which is why screening is so important. Symptoms do not generally appear until the disease is quite advanced, which decreases the likelihood treatment will be effective. There are a number of screening options available.
For colon cancer, colorectal polyps Mayo Clinic. Colon polyps. (July 2007) are the clearest warning signs. Polyps, small growths on the colon wall that look like a ball on a stick, are not cancerous (they are “benign”) to begin with, but they may become cancerous. A new polyp, for example, has only a 2.5% chance of becoming cancerous in its first five years. After 20 years, however, that same polyp has a 24% chance of becoming cancerous.
Larger polyps (5mm, or about the size of a pencil eraser) are more likely to develop cancer. Some people have more than one polyp: certain families have genes that cause them to develop thousands of polyps, increasing the probability that they may develop the disease. (source)
Risk factors for polyps and colon cancer include: (source):
- Age – 90% of people diagnosed are over 50
- smoking
- drinking – people who smoke and drink are at four times average risk
- lack of exercise
- diet low in fibre and heavy in meat, fat, and protein
- obesity
- personal history of ulcerative colitis or Crohn's disease
- family history of polyps, colon cancer, or cancers of female reproductive organs (ovarian cancer, endometrial cancer, breast cancer)
- Lynch syndrome
Polyps and colon cancer both cause the intestine to bleed slowly and steadily. Bloody stools are caused by many things, however, and may not be noticeable. Because of this, iron-deficiency anaemia Mayo Clinic. Iron-deficiency anemia. (March 2007). may be a warning sign. If you experience either of these, see your doctor or go to your local public health unit.
You may also experience: (source) some of the following:
- a change in your bowel habits, including diarrhoea or constipation or a change in the consistency of your stool for more than a couple of weeks
- rectal bleeding or blood in your stool
- persistent abdominal discomfort, such as cramps, gas or pain
- abdominal pain with a bowel movement
- a feeling that your bowel doesn't empty completely
- weakness or fatigue
- unexplained weight loss
How is it treated?
In general, there are three main treatments or colon cancer: surgery, radiation and chemotherapy.
Surgery – this is most likely to cure colon cancer, but can only be used for stages I, II and II tumours
Radiation therapy and chemotherapy – if you are diagnosed with stage II or III tumours, you will probably have to undergo these treatments in addition to surgery
If you have been diagnosed with colon cancer, there are some strategies that can help you cope:
- Know what to expect: do research, ask questions
- Take an active role in your treatment: don’t let others make the important decisions for you
- Make sure you have a strong support system: Friends and family are your most important allies — let them help you. Find a support group to share your experience with people who are going through the same thing.
- Set reasonable goals for yourself: they help you take control and have a sense of purpose
- Take time for yourself: Eat well, relax, rest. These help fight the stress and fatigue. Plan ahead for downtimes when you may need to rest a bit longer or limit what you do.
Can I prevent or avoid colon cancer?
With colorectal cancer, an ounce of prevention is worth a pound of cure: improve your diet, lose weight and get more exercise to reduce your risk. Avoid risky behaviours such as smoking. Get tested regularly.
Diets high in vegetables, fruit, and fibres have been shown to help prevent colon cancer. Some evidence suggests that the following supplements may also help protect you, however, more studies are still being done to confirm this: (source)
- ASA (one a day)
- selenium (a mineral)
- turmeric (a spice)
The most important thing you can do, however, is to get tested for polyps if you have risk factors. Regular testing for and removal of colon polyps can help prevent colon cancer in the same way that not smoking can dramatically reduce your risk of lung cancer.
Polyps can be removed without surgery using an endoscope. People who have had polyps removed are at more than twice the average colon cancer risk for their age. People who leave them in, however, are at eight times the normal risk.
Donna MacLeod, for Consumer Health Information Service, Toronto Public Library
Further reading
Canadian Cancer Society.
Colorectal Cancer Association of Canada (website)
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Toronto: 60 St. Clair Avenue East Suite 204 Toronto, Ontario, Canada M4T 1N5 Telephone: (416) 920-4333 Fax: (416) 920-3004 E-Mail: information@colorectal-cancer.ca
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Toll-free information line: 1-877-50-COLON
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Provides many useful resources, including information on colorectal cancer and support services (online, in person and on the phone). News, research, advocacy, fundraising and a lot of very useful information also appears.
Healthy Ontario.
Mayo Clinic.
