Colorectal cancer screening (colon and rectum)

Colorectal cancer screening (colon and rectum)

Description

Target persons

Screening method

Advantages and limits of RSOSi screening

Some numbers

Description

Colorectal cancer, commonly known as colon cancer, usually develops very slowly. A person can have this cancer for years before they have symptoms.

health tips

Screening aims to detect and treat colorectal cancer before signs and symptoms appear. Generally, at the time of screening, the cancer is at an early stage and the possibilities of cure are better.

Target persons

Screening is mainly aimed at people aged 50 to 74, since the risk of developing colorectal cancer increases from the age of 50.

Screening could start before the age of 50 for people who are at a higher risk of developing colorectal cancer.

Screening method

Medium risk people

In Quebec, screening for colorectal cancer in people at medium risk, without symptoms and without any other risk factor, is recommended every 2 years. Screening is done using the stool occult blood immunochemical test (RSOSi). This test does not tell whether you have colorectal cancer or not, but it can detect the presence of blood in your stool, which may be a sign of cancer.

When the RSOSi test result indicates the presence of blood in the stool, the doctor recommends another examination to establish the diagnosis, the long colonoscopy. This exam allows you to visualize the interior of the large intestine to check whether or not there is cancer.

People at higher risk

In the case of people who are at higher risk, the doctor determines the screening method based on the specific situation of each person.

If you are in this situation, discuss with your doctor the recommendations that apply to you.

Advantages and limits of RSOSi screening

You can decide whether or not to get tested for colorectal cancer. It’s a personal choice, up to you. If you have any questions or concerns about this, discuss them with your doctor.

Benefits

Screening decreases the risk of dying from colorectal cancer. Out of 1,000 people who pass a screening test, 5 deaths are prevented.

Colorectal cancer usually develops very slowly. Having the Rossi test every 2 years, therefore, increases the chances that cancer will be discovered and treated at an early stage. The necessary treatments could also be less aggressive.

In addition, when a long colonoscopy is necessary, the doctor can see if there are polyps on the inner walls of the large intestine. Polyps are small masses of flesh that can develop into colorectal cancer. The doctor can remove them before they become cancerous.

Limits

Despite all its advantages, screening with the RSOSi test is not perfect.

In some cases, the test can detect blood in the stool when there is no cancer or polyp.

This is rare. Out of 1,000 people who take the test, about 15 people receive such a result. These few people then undergo a long colonoscopy which is not necessary and can sometimes have polyps removed unnecessarily.

In addition, long colonoscopy can lead to certain complications. For more information, see the Long Colonoscopy page.

On the contrary, people who have colorectal cancer may receive a normal test result.

This situation occurs for about 20% of people who have colorectal cancer. Their cancer went unnoticed. No screening test, even a long colonoscopy, can guarantee that cancer will be detected. This is why it is recommended to repeat the RSOSi test every 2 years, as this increases the chances that the cancer will be detected.

In addition, screening can detect cancer when it is at an early stage, thereby increasing the chances of recovery. However, a number of people die from colorectal cancer each year, even if they had been screened.

Some numbers

Out of 1,000 people who pass the RSOSi test, 36 will receive an abnormal test result and then have a long colonoscopy. Of these 36 people:

4 will have colorectal cancer;

17 will have one or more polyps removed;

15 will not have cancer or polyps.