Age to start colorectal cancer screening in Canada: Watching brief

December 3, 2025

colorectal cancer screening
The purpose of the Watching Brief on the Age to Start Colorectal Cancer Screening in Canada is to summarize and contextualize the evidence on the age to start colorectal cancer screening to inform provincial and territorial decision making on lowering the age to start colorectal screening. This Watching Brief was developed in 2023-2024 by a Working Group of experts in colorectal screening from across the country.

Key takeaways

  • Although empirical data describing the effectiveness of colorectal screening in younger persons is quite limited at this time, the field is evolving rapidly, and it is likely that evidence will emerge in the next year or two.
  • Regarding the changing epidemiology of colorectal cancer in Canada, the most notable increase in incidence rates in younger persons is among those 45-50 years. However, the incidence is also increasing among those in even younger age groups, and a lowering of the age to start colorectal screening to age 45 would not address this.
  • If the age to start colorectal screening is lowered to 45 years, this would lead to clinical impact in terms of a reduction in colorectal cancer incidence and deaths but would require an increase in FIT kits and colonoscopies as well as staffing resources.
  • If a decision is taken to lower the age to start colorectal screening, additional resources will be required to ensure this does not adversely impact access to diagnostic colonoscopy.
  • If a decision is taken to lower the age to start colorectal screening, there should be a clear plan in place beforehand to monitor and to evaluate the implementation, so that a full picture of its impacts on clinical outcomes and resources can be determined.
  • Regardless of the decision whether to lower the age to start colorectal screening, it is important that younger persons with large bowel symptoms, such as rectal bleeding, undergo prompt investigation.

Why a “Watching Brief”?

Recognizing that the body of evidence on the topic is evolving rapidly – in part because of the US experience in screening younger persons that is well underway – the Working Group recognizes the need to update this document as the evidence evolves. Hence the term Watching Brief – to indicate that the Working Group is tracking the evidence as it accumulates and will update this document as needed.

Downloadable document