Why screening is critical for colorectal cancers

With nearly 2 in 5 Canadians expected to be diagnosed with cancer in their lifetime, about 40% of the people we see in our day to day lives – our friends, family, neighbours and co-workers – may hear the words, “you have cancer.”

Whether you or a loved one hear those words at an early or late stage of the disease can make all the difference.

The 2023 Canadian Cancer Statistics special report explores the stage in which cancers are diagnosed in Canada, with a focus on the top 4 most commonly diagnosed cancers (lung, colorectal, female breast and prostate) and cervical cancer.

A critical takeaway from this report was that almost half of colorectal cancers are found after they have already spread – in stage 3 or 4 – despite availability of screening programs.

Cancer stage and diagnosis

Staging describes or classifies a cancer based on how much cancer is in the body and whether it has spread when it is first diagnosed.

Healthcare professionals often assign an overall stage from 1 to 4. Generally, the higher the number, the more the cancer has spread. This is the case for most cancers, including colorectal.

Catching colorectal cancer early

Colorectal cancer is the second leading cause of cancer death in Canada, accounting for an estimated 9,400 deaths in 2017 alone. The 5-year survival rate for colorectal cancer diagnosed at stage 4 is less than 15%. But that rate increases to 90% when it’s diagnosed earlier, at stage 1. Because colorectal cancer often does not cause any signs or symptoms in its early stages, colorectal cancer screening is critical to catching it early and increasing the chance of survival.

"I encourage everyone to take charge of their own health and talk to their doctor about screening," shares Jeff, a colorectal cancer survivor. "Don't wait until you have symptoms like I did. I was lucky that my cancer was caught early and had not spread beyond my colon. If my doctor had not recommended the stool test, who knows where I would be today."

Jeff holding an acoustic guitar

Screening for colorectal cancer is easy and convenient, and it can help catch cancer early or even before it starts. Colorectal cancer screening starts with a simple test that can often be done at home. The test is designed to check your stool for blood. Pre-cancerous polyps and cancerous tumours in the colon have blood vessels that can release a small amount of blood into the stool. Stool tests check for this hidden blood, which you can’t see with your eyes. Having blood in your stool doesn’t always mean that you have polyps or cancer. If a stool test shows traces of blood in the stool, more tests need to be done to find out where the blood is coming from and why.

We recommend that Canadians aged 50 to 74 who are not at high risk for colorectal cancer get screened every 2 years with a simple stool test.

You may be at high risk of colorectal cancer if, for example, your family member has been diagnosed with colorectal cancer or you have a personal history of certain types of polyps in the colon or rectum. We encourage all Canadians to speak with their healthcare providers about their risk of cancer and become aware of what screening strategies are right for them.

Today, more than 64% of Canadians diagnosed with cancer will survive compared to about 55% in the early 1990s. It’s clear that progress is being made, but if cancer was caught earlier for more Canadians, we could improve and save more lives. Speak to your healthcare provider and learn more about screening.

The Canadian Cancer Statistics publication is developed through a partnership between the Canadian Cancer Society, the Public Health Agency of Canada and Statistics Canada, in collaboration with the provincial and territorial cancer registries. Read the full report.