Colorectal cancer

Dr. Harminder Singh Gastroenterologist, Associate Professor with University of Manitoba, Co-Lead of Hereditary Gastrointestinal Cancer Clinic at CancerCare Manitoba, and former member of the Canadian Task Force on Preventive Health Care
Last updated: May 29, 2024

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Over 90% of colorectal cancers are diagnosed over the age of 50. This is why routine screening is generally directed at people between ages 50 and 74. However, some individuals under 50 can be at higher risk and should start screening at a younger age, and screening is sometimes recommended for those age 75 and older depending on personal risk factors. 

Who has a higher risk?

Research has shown that a history of colorectal cancer in your immediate family means you are at higher risk. Immediate, or first degree, family means your siblings, children, or parents. 

Aside from your family history, you could be at higher risk of developing colorectal cancer if you have a personal history that includes:

  • Inflammatory bowel disease (Ulcerative colitis or Crohns Disease) with associated colitis for many years

  • Lynch syndrome or familial adenomatous polyposis (FAP)

  • A previous diagnosis of colorectal cancer or polyps 

  • Previous cancer treatment under the age of 36 that involved radiation therapy in the abdomen, pelvis, or whole body. 

What should I do if I’m at increased risk?

If you think you might be at increased risk, you should talk to your doctor. Based on your individual risk, your doctor may recommend screening start earlier than age 50 or continue after age 74. Learn more about colorectal cancer screening.

If you have a family history of colorectal cancer or a polyp in a first degree relative, screening may be recommended to start when you are 40 years old instead of 50, or 10 years younger than when your relative was diagnosed, whichever comes first. So, for example:

  • If your mother was diagnosed at age 65, you should start screening when you are 40.

  • If your father was diagnosed at age 45, you should start screening when you are 35.

Don’t ignore symptoms – get tested!

Routine screening is for people without symptoms to catch a disease before symptoms emerge. If you have symptoms such as ongoing rectal bleeding, anemia, abdominal pain or unexplained weight loss, talk to your doctor to get an appropriate test and diagnosis. While these are symptoms of colorectal cancer, there are also many other conditions that can cause them. 

How can I lower my risk?

To lower your risk of colorectal cancer:

  • Quit smoking. Do not start smoking, and avoid second-hand smoke.

  • Avoid alcohol. The less you drink, the more you reduce your risk.

  • Maintain a healthy weight.

  • Move more.

  • Eat healthy.

Key takeaways

  • Screening may be recommended for those at higher risk under age 50 or over 75.

  • When colorectal cancer is caught early through screening, 9 out of 10 people can be cured.

  • Screening is for people who don’t have symptoms. If you have symptoms of colorectal cancer, you should talk to your doctor to get a test and diagnosis.

  • If you have Ulcerative colitis or Crohns disease, history of colon cancer or polyps, Lynch Syndrome or colonic polyposis or family history of colon cancer or polyps, ask your doctor about the screening that is right for you.

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