How to use it
Answer every question about the index colonoscopy (the one you’re setting the interval after). The result is the shortest interval triggered by any finding, with the rule and its source. If a finding isn’t covered by Ontario, the source line says so, and the tool falls back to USMSTF 2020 or ESGE 2020.
This tool is for people at average or increased risk because of family history. It does not apply to IBD, hereditary syndromes (Lynch syndrome, FAP) or a personal history of colorectal cancer.
Ontario rules at a glance
| Finding at colonoscopy | Ontario next step |
|---|---|
| No polyps, or small (<10 mm) hyperplastic polyps in rectum or sigmoid | FIT in 10 years |
| 1–2 low-risk adenomas (tubular, <10 mm, no high-grade dysplasia) | FIT in 5 years |
| Any low-risk sessile serrated lesion (<10 mm, no dysplasia) | Colonoscopy in 5 years |
| High-risk polyps: adenoma ≥10 mm, tubulovillous or villous, high-grade dysplasia, ≥3 adenomas, SSL ≥10 mm or with dysplasia, traditional serrated adenoma | Colonoscopy in 3 years |
| More than 10 adenomas | Colonoscopy within 1 year and genetic assessment for FAP |
| Polyp ≥20 mm removed piecemeal | Colonoscopy within 6 months |
| Serrated polyposis syndrome | Colonoscopy in 1 year, then every 1–2 years |
| Increased-risk family history | Colonoscopy every 5 years, or the surveillance interval if shorter |
After a high-risk adenoma, if the next colonoscopy shows nothing worse than low-risk adenomas, the following one is in 5 years; if high-risk adenomas are found again, 3 years. For serrated lesions and piecemeal resections, Ontario leaves later intervals to the endoscopist because the evidence is insufficient.
What changed on 1 July 2026
- FIT from 45. People at average risk do FIT every 2 years from 45 to 74.
- One relative at 60 or older is average risk. These people now do FIT, not colonoscopy.
- Increased risk is one first-degree relative diagnosed before 60, or two or more at any age. Start at 40, or 10 years before the youngest relative’s diagnosis (whichever comes first), and repeat colonoscopy every 5 years.
- Relatives with polyps only, and second-degree relatives, don’t raise the risk category.
- Stopping. Routine screening ends at 74. At 75–85, screen only if the benefits outweigh the risks. Over 85, Ontario strongly recommends against it. The same stop ages now apply to people at increased risk.
- Billing. OHIP colonoscopy codes (Z492, Z493, Z498, Z499) now follow the CCC recommendations instead of fixed intervals.
Where Ontario differs
Each line reads Ontario / USMSTF 2020 / ESGE 2020.
- 1–2 small tubular adenomas: FIT in 5 years / colonoscopy in 7–10 years / back to screening.
- 3–4 small adenomas: 3 years / 3–5 years / no surveillance (1–4 is low risk in ESGE).
- Villous histology alone: 3 years / 3 years / not high risk.
- Low-risk SSLs: 5 years for any number / 1–2: 5–10 years, 3–4: 3–5 years, 5–10: 3 years / back to screening.
- Hyperplastic ≥10 mm: not covered / 3–5 years / 3 years.
- Piecemeal ≥20 mm: within 6 months, then at the endoscopist’s discretion / 6 months, 1 year, then 3 years / 3–6 months, then 12 months.
- Family history: shortens to colonoscopy every 5 years / use the shorter interval / suggests against shortening.
- Stopping: screening ages, no surveillance-specific age / no 2020 stop age / stop at 80.
Evidence
- Low-risk adenomas. Ontario’s FIT-in-5-years rule rests on Dubé 2017: people with low-risk adenomas had a lower colorectal cancer risk than the general population (SIR 0.68) and lower cancer mortality (SMR 0.75).
- Cross 2020 (Gut). In 28,972 UK patients, one surveillance visit lowered colorectal cancer incidence by 40–50% in every risk group, including low risk (HR 0.56). But even without surveillance, low-risk patients’ incidence was similar to the general population (SIR 0.86). The authors concluded such patients could be managed by screening rather than surveillance. Surveillance is not useless; low-risk patients just don’t need more than screening.
Pitfalls
- Quality first. Ontario intervals assume adequate preparation, a complete exam to the cecum and complete removal. Fix those before you set a surveillance interval.
- Proximal or large hyperplastic polyps. Many are misclassified sessile serrated lesions. Review the pathology before choosing a long interval.
- Typo in the 2026 provider tool. Its footnote lists “>10 mm tubular adenoma” as high risk; every other Ontario source says 10 mm or larger. This tool uses ≥10 mm.
- Under 45. Ontario FIT starts at 45, so “FIT in 5 years” for a 35-year-old means FIT at 45.