After high-risk adenoma removal, first surveillance at five years was non-inferior to three

Design

Randomised non-inferiority trial, 8 European countries, interim analysis (EPoS II)

Population

10,799 patients after removal of high-risk adenomas

Primary outcome

Cumulative colorectal cancer incidence (10-year primary; 5-year interim)

Effect

0.77% vs 0.82% at 5 years; upper 99.12% CI bound 0.68 points (margin 0.7)

EPoS II is a randomised non-inferiority trial in eight European countries. It enrolled 10,799 people after removal of high-risk adenomas — at least one adenoma of 10 mm or more, high-grade dysplasia or villous histology, or three to ten adenomas — and assigned the first surveillance colonoscopy to 5 years or to the guideline-recommended 3 years.

At this interim analysis after 5.5 years, the 5-year cumulative colorectal cancer incidence was 0.77% in the 5-year group and 0.82% in the 3-year group (difference −0.05 points). The upper bound of the one-sided 99.12% confidence interval, 0.68 points, was within the 0.7-point non-inferiority margin. Stage distribution did not differ materially. Five patients died of colorectal cancer: 3 in the 5-year group and 2 in the 3-year group.

Colonoscopy capacity is limited everywhere, and surveillance of people with previous polyps consumes a large share. This result supports waiting five years before the first surveillance colonoscopy in high-risk adenoma patients, freeing capacity for symptomatic and screening patients. The final 10-year analysis will be definitive, and the result assumes a high-quality index colonoscopy with complete polyp removal.

• After complete removal of high-risk adenomas at a good-quality colonoscopy, consider first surveillance at 5 years rather than 3.
• Confirm that the index examination was complete, with adequate bowel preparation and caecal intubation.
• Shorter intervals remain appropriate for piecemeal resection of large polyps, poor preparation or incomplete examination.
• Tell patients to report new symptoms at any time — surveillance intervals do not replace symptom review.
• Watch for guideline revisions once the 10-year analysis reports.

Why it matters

It could release a large share of surveillance colonoscopy capacity for patients who need it more.

Don't overread it

This is an interim 5.5-year analysis of a trial designed for 10-year outcomes; guideline change should await the final result.

The statistics, in plain English

The trial set a margin of 0.7 percentage points — the most extra cancer it would accept. The worst plausible difference (0.68 points) fell just inside it, so non-inferiority was shown, but with little room to spare.

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