Endoscopic surveillance in serrated polyposis syndrome: a randomized controlled trial comparing two- vs. three-year colonoscopy intervals
Jorge Lopez Vicente (Móstoles, Spain), Daniel Rodriguez Alcalde (Móstoles, Spain), Luis Hernandez Villalba (Aranda de Duero, Spain), Patricia Pedregal Pascual (Barcelona, Spain), Luisa Adan Merino (Madrid, Spain), Francisco Polo Ortiz (Bilbao, Spain), Xabier Bessa Caserras (Barcelona, Spain), José Carlos Marín Gabriel (Madrid, Spain)
Background

Serrated polyposis syndrome (SPS) is currently recognized as the most common colorectal polyposis syndrome, with an increased risk of colorectal cancer (CRC) reported in numerous studies. The overall CRC incidence during surveillance is 2.8%, and the five-year cumulative incidence of advanced neoplasia (AN) ranges from 22.1% to 44%. The European Society of Gastrointestinal Endoscopy (ESGE) guidelines recommend surveillance every one or two years, depending on the findings of the last colonoscopy: ≥1 advanced lesion or ≥5 relevant polyps. Since a 2-year follow-up has not been associated with an increased incidence of AN, extending the interval beyond two years has been proposed as a potentially safe alternative. This study aimed to compare the incidence of AN between two-year and three-year colonoscopy surveillance intervals in SPS patients.

Method

A randomized, controlled, multicenter study was conducted from February 2021 to October 2024 across six centers in Spain. Patients meeting the 2019 WHO SPS criteria I or II and already under surveillance, having completed the "clearing phase," were randomized into two groups for their subsequent surveillance procedure: group 1, colonoscopy after two years; and group 2, colonoscopy after three years. Patients had no advanced adenomas, no advanced serrated polyps, and fewer than five "relevant polyps" in their previous colonoscopy. A non-inferiority analysis was conducted to compare outcomes between the groups. 

Results

A total of 127 patients were included, with 46.5% women and a mean age of 66.2 years. Seventy-one patients were randomized to the 2-year colonoscopy group, and 56 to the 3-year group; 66.1% met SPS criterion II, and 33.9% met criteria I or I+II. A total of 756 lesions were resected, of which 2.5% were advanced adenomas or advanced serrated lesions, and no CRC cases were detected. No increased risk of AN was observed in the 3-year group (10.7%) compared to the 2-year group (7%): OR 1.584 (95% CI: 0.457–5.487; p = 0.465). SPS criteria were also not associated with AN risk: OR 1.920 (95% CI: 0.679–5.431; p = 0.201). Univariable and multivariable analyses identified no other risk factors for AN.

Conclusion

In SPS patients with a 2-year colonoscopy recommendation from ESGE guidelines, extending the surveillance interval to three years does not increase the risk of AN. Extending the surveillance interval to three years in this patient population could safely reduce the colonoscopy burden on endoscopy units.

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