Colorectal Cancer Prevention

Preventing colorectal cancer

The risk of developing colorectal cancer depends on various factors. While you cannot change some risk factors such as age or family cancer history, there are certain things that you can do to help lower your cancer risk.

Follow cancer screening guidelines

Screening for colorectal cancer means looking for the presence of cancer or pre-cancer in someone who does not show any signs or symptoms of the disease.

Since colorectal cancer almost always develops from precancerous polyps (growths), participating in regular screening can help to find and remove these polyps before they become cancerous. Screening can also help to find colorectal cancer when it is in the early stages, when it has not grown beyond the colon or rectum and there is a better chance of successful treatment. Be sure to talk to your doctor about when you should start regular colorectal cancer screening.

In Canada, colorectal cancer screening begins at 50 years of age for average risk individuals. Screening is usually done with a stool test every 2 years. For individuals over the age of 75, talk to your doctor to discuss the most appropriate screening options.

Follow-up for positive stool tests should include either a colonoscopy or flexible sigmoidoscopy.

It is recommended that individuals at high-risk for colorectal cancer undergo more frequent screening and at an earlier age than people at average risk. You may be at a higher risk for colorectal cancer if you have:

A strong family history of colorectal cancer or polyps. Talk to your doctor to find out if you may benefit from genetic counseling to best review your family cancer history and determine the likelihood of having an inherited cancer syndrome
An inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
An inherited cancer syndrome such as Lynch syndrome or familial adenomatous polyposis (FAP)

Be sure to discuss your personal colorectal cancer risk with your doctor to develop an appropriate screening plan.

Learn more about colorectal cancer risk factors

Know the Symptoms of Colorectal Cancer

Colorectal cancer may not cause symptoms in the early stages of the disease. Since colorectal cancer almost always develops from precancerous polyps or growths in the colon or rectum, participating in regular screening can help to find and remove these polyps before they become cancerous. Be sure to talk to your doctor about when you should start regular colorectal cancer screening.

Symptoms may include:

Unexplained changes in bowel habits, such as constipation or diarrhea
Change in size/shape/consistency of stools, such as being narrower than usual
The urge to have a bowel movement but nothing passes
Rectal bleeding

Blood in or on the stool, ranging from bright red to dark black
Persistent abdominal pain/discomfort including bloating, fullness, cramps, gas pain
Unexplained weight loss
Weakness and fatigue, which may be accompanied by iron deficiency anemia

Learn more about colorectal cancer symptoms

Colorectal cancer symptoms - list of symptoms and what to do

If I Experience Symptoms, When Should I See a Doctor?

As soon as possible. Many of these symptoms may be caused by other gastrointestinal conditions, such as ulcers, Crohn’s disease or hemorrhoids, but they should always be discussed with your doctor to determine the correct diagnosis.

Even though colorectal cancer is more commonly diagnosed in people over the age of 50, rates are on the rise in younger adults. Regardless of your age, if you are experiencing symptoms, talk to your doctor. For more information on early age onset colorectal cancer, see our Never Too Young (N2Y) Program.

Lifestyle Factors and Colorectal Cancer Risk

The recommendations below come from the World Cancer Research Fund and the American Institute for Cancer Research report “Diet, nutrition, physical activity and colorectal cancer” which systematically gathered and analysed global scientific research on the impact of lifestyle factors on colorectal cancer risk.

Diet, body weight and physical activity

There is strong evidence to support that:

1

Eating foods rich in dietary fibre lowers the risk of colorectal cancer. This includes legumes such as beans and lentils, fruits and vegetables, and whole grains.
2

Eating whole grains lowers the risk of colorectal cancer. This includes whole wheat, oats, quinoa, brown rice, and popcorn.
3

Consuming processed meats (such as deli meats, ham, sausage, hot dogs, or pepperoni) and red meat increases your risk of developing colorectal cancer
4

Drinking two or more alcoholic drinks every day increases the risk of colorectal cancer.

Take home message: Eating more vegetables, fruits, and whole grains while limiting red and processed meats and alcohol consumption may help lower your risk.
5

Being overweight (BMI: 25.0 – 29,9) or obese (BMI: 30.0 and above) increases the risk of developing colorectal cancer.

Take home message: Maintaining a healthy body weight may help lower your risk.
6
Being physically active lowers the risk of colorectal cancer. 30 minutes of daily moderate to vigorous physical activity is recommended. This could include:
- Walking or riding your bike to work
- Household chores such as cleaning or yard work
Take home message: Being physically active and maintaining a healthy body weight may help lower your risk.

For more information about nutrition and healthy living for cancer prevention, visit our Foods that Fight Cancer website.

Quitting smoking

Long-term smoking increases the risk of colorectal cancer and many other cancers. If you smoke and are thinking about quitting, or if you have already quit and need support, see support services by province and territory.

Take home message: Quitting smoking may help reduce your risk.

Frequently Asked Questions

How does red and processed meat consumption impact colorectal cancer risk?

Red meat contains heme iron in high levels which has been shown to promote the development of colorectal tumours. When red meat is cooked at high temperatures, such as through grilling or charbroiling, compounds known as polycyclic aromatic hydrocarbons are formed. These compounds have been linked to cancer development.

Processed meats include meats that have been preserved by smoking, salting, curing or adding chemical preservatives. Examples include deli meats, bacon, hot dogs, sausages, and pepperoni. Similar to red meats, processed meats are often cooked at high temperatures, increasing the number of polycyclic aromatic hydrocarbons present, which have cancer-causing potential. Furthermore, processed meats contain chemicals known as N-nitroso compounds derived from nitrite-based chemical preservatives. These compounds are known to be carcinogenic in humans.

It is recommended that for people who eat meat, eat no more than moderate amounts of red meat, such as beef, pork and lamb, and eat little, if any, processed meat.

Source: World Cancer Research Fund/American Institute for Cancer Research. Diet, Nutrition, Physical Activity and cancer: a Global Perspective. Continuous Update Project Expert Report 2018. Available at dietandcancerreport.org

How does physical activity lower the risk for colorectal cancer?

The primary mechanism through which physical activity is believed to lower the risk of developing colorectal cancer is by reducing body fat levels. This, in turn, helps to reduce insulin resistance and inflammation, which have both been linked to the development of colorectal cancer.