Know Your Risks, Know Your Options: The Complete Guide to Colorectal Cancer Screening

Danyelle Lachowich ND (prov.)
2 days ago
7 min read

Colorectal model with blue ribbon over doctor's shoulder. Text: "Know Your Risks, Know Your Options: Colorectal Cancer Screening Guide.

Colorectal Cancer: What is it?

Colorectal cancer refers to cancers that begin in the cells of the colon or rectum, which are parts of the digestive system (1). While these are technically two distinct cancers, colon cancer and rectal cancer, they are grouped together as there is no absolute border between the two organs (1). Colorectal cancer starts with changes to the cells that line the wall of the colon or rectum that can lead to small growths we call polyps (1, 2). While not all polyps become colorectal cancer, if they are left untreated, they can eventually develop into cancer (2).

A diagram of the human digestive system, with labels including: mouth, esophagus, liver, stomach, duodenum, pancreas, colon, large intestine, small intestine, anus, and rectum

National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.

Just the Numbers

Colorectal cancer was the 4th most diagnosed cancer in Canada in 2024 and was the 2nd leading cause of cancer-related deaths in men and the 3rd leading cause of cancer-related deaths in women (3).
In Alberta, 1 in 17 women and 1 in 14 men are expected to develop colorectal cancer in their lifetime (4).
It is thought that about 46% of colorectal cancer cases in Canada could be prevented by addressing diet and lifestyle factors (5).
The 5-year survival rate for Stage I colon cancer and rectal cancer is 92% and 91%, respectively (6).

Risk Factors

Risk factors are any behaviours, substances, or conditions that can contribute to the development of a cancer (7). In most cases, cancer develops due to a combination of risk factors, but in other cases, individuals may have none of the factors below (7).

Non-Modifiable

These are risk factors that are out of your control (8). While you may not be able to change the following risk factors, building awareness of your non-modifiable risk factors helps to ensure you receive appropriate screening.

Age: Most colorectal cancer cases occur in individuals over the age of 50 (7, 8).
Family history of colorectal cancer is the second most common risk factor for colorectal cancer (8). First-degree relatives (parents, siblings, children) with a history of colorectal cancer increase your risk of developing colorectal cancer (7, 8).
A personal history of colorectal cancer or colorectal polyps, or adenomas, increases your risk of developing colorectal cancer (7, 8).
Personal history of inflammatory bowel disease (Crohn’s and ulcerative colitis) increases risk due to the inflammation of the lining of the colon (7, 8).
Specific rare conditions, such as Lynch Syndrome and Familial Adenomatous Polyposis (FAP) (7).

Modifiable

Modifiable risk factors include many lifestyle choices that you can make to help reduce your overall risk of developing colorectal cancer (8). It is important to note that taking action regarding modifiable risk factors is not a guarantee that you won’t develop colorectal cancer, but they go a long way in reducing risk and supporting overall health and well-being.

Physical activity: Reduced physical activity has been linked to a higher risk of developing colorectal cancer (7, 8).
Weight management: Individuals who are considered overweight or have a higher BMI have been shown to have an increased risk of colorectal cancer, although this link appears to be most relevant in men (7, 8).
Alcohol Use: The less alcohol you drink, the lower your cancer risk (7, 8).
Smoking: Risk of colorectal cancer appears to increase the longer a person smokes and with the total amount a person smokes (7, 8)
Dietary factors such as consumption of red meat, consumption of processed meat, and low fibre intake (7, 8).

Why do we screen?

As we noted above, up to 46% of colorectal cancer cases in Canada are preventable with diet and lifestyle changes (5). One of the risk factors that was not discussed above was screening (8). Regular colorectal cancer screening helps to detect changes in the colon and rectum at earlier stages to allow for prompt and effective treatment (9, 10).

Screening is a process by which we assess individuals who have no symptoms of colorectal cancer for early signs of cancer (9, 10).

Who do we screen?

In average risk individuals, regular screening is recommended for those between the ages of 50 to 74 years (9, 11). Screening recommendations change when a person is part of the increased risk population (9).

Individuals in the increased risk population include:

Individuals with one first-degree relative diagnosed with colorectal cancer and/or high-risk adenoma (11).
Individuals with two or more relatives diagnosed with colorectal cancer and/or high-risk adenoma (11).
Individuals with a personal history of colorectal cancer, colonic adenomas, or inflammatory bowel disease (11).
Individuals with high-risk conditions such as Lynch Syndrome or FAP (11).

If you are unclear of your risk category or you have current signs of colorectal cancer, it is recommended that you speak with your health care provider (9).

When do we screen?

Average Risk Populations

As noted above, for individuals of average risk, screening occurs between the ages of 50 to 74 and is recommended on a yearly basis (9).

High Risk Populations

Individuals with one first-degree relative diagnosed with colorectal cancer and/or high-risk adenoma after the age of 60 should begin screening at age 40 (11).
Individuals with one first-degree relative diagnosed with colorectal cancer and/or high-risk adenoma before the age of 60 should begin screening at age 40, or 10 years before the age at diagnosis, whichever is earlier (11).
Individuals with two or more relatives diagnosed with colorectal cancer and/or high-risk adenoma begin screening at age 40, or 10 years before the youngest age of diagnosis, whichever is earlier (11).
Individuals with a personal history of colorectal cancer, colonic adenomas, or inflammatory bowel disease should receive ongoing follow-up by colonoscopy as recommended by their local screening program or endoscopist (11).
Individuals with high-risk conditions such as Lynch Syndrome or FAP should have an established relationship with their local colorectal cancer screening program or an endoscopist for ongoing care and monitoring (11).

How do we screen?

Fecal Immunochemical Test (FIT)

FIT is an at-home screening test that checks your stool for traces of blood that you cannot see with the naked eye (9). To complete the test, you collect a small sample of stool from your bowel movement before returning the kit to the lab for testing (9). Results are then sent to your health care provider for follow-up (9).

The FIT is used in individuals of average risk and should be repeated on a yearly basis (11). The yearly screening is recommended as there is still a chance that the test will miss blood in the stool if a cancer or polyp is not bleeding at the time of the test. Yearly screening provides the best chance of early detection of cancerous or precancerous changes (9).

If your FIT returns positive for blood, you will be promptly referred for a colonoscopy (11).

The FIT should not be used if:

You have symptoms of colorectal cancer, such as bloody stools or recent changes in bowel habits (11).
You have had a high-quality colonoscopy in the past 10 years (11).
You have an acute gastrointestinal condition where bleeding is likely, such as inflammatory bowel disease, acute gastroenteritis, C. difficile colitis, or actively bleeding hemorrhoids or anal fissures (11).

In Alberta, you can access a FIT via your medical doctor, healthcare provider, naturopathic doctor, or online via screeningforlife.ca. You can also call the Alberta Health Services Screening Programs at 1-866-727-3926.

Colonoscopy

If you are ineligible for screening with FIT, then you will most likely be recommended screening via colonoscopy (9). A colonoscopy is a test that uses a long, thin, flexible tube with a light and small camera on the end to view the inside lining of the colon and rectum (9). This is a test that can help doctors view any polyps or cancers that may be present and remove them or take biopsies for further testing (9).

Colonoscopies will also be used to check on symptoms of colorectal cancer, such as rectal bleeding, abdominal pain, and changes in bowel habits; monitor after treatment for colorectal cancer; and follow up after an abnormal FIT (9).

What else can you do?

Stay Active!

Engaging in at least 30 minutes of daily moderate-intensity physical activity can reduce your risk of colorectal cancer (12).

Limit or Omit Alcohol

Any alcohol consumption can increase your risk of cancer (12, 14). If you choose to drink alcohol, it is best to consume as little as possible and have no more than 2 standard drinks per week. For more information on reducing alcohol consumption, check out our Sober Curious blog post.

Reduce Your Processed and Red Meat Consumption

Diets high in red meat and/or processed meat have been shown to increase the risk of colorectal cancer (12, 13). Try to limit your intake of these to no more than one serving (3 ounces) per week.

Eat Enough Fibre

Fibre is key to keeping bowel movements regular and the digestive system healthy. Reduced risk of colorectal cancer was seen in individuals eating adequate fibre, especially from whole grains (15, 16). Individual fibre requirements do vary, but a good rule of thumb is to get at least 25-30g per day.

Get Screened!

Confused on where to start? Use the map below to help determine when and how you should be screened. When in doubt, discuss your screening needs with a health care provider.

An infographic for colorectal cancer risks assessments, branching off into "High Risk" and "Average Risk" sections.

Other Resources

2SLGBTQIA+

Colorectal cancer screening guidelines are the same regardless of gender identity or sexual orientation. Specific information sheets on cancer screening in the 2SLGBTQIA+ community can be found here.

*Disclaimer: The information contained within this post is for general educational and information purposes only; no doctor-patient relationship is formed. It is not professional medical advice, diagnosis, treatment, or care, nor is it intended to be a substitute therefore. If you have any concerns or questions about your health, always seek the advice of a qualified healthcare professional.