Post written by Sandra Baile-Maxía, MD, PhD, and Rodrigo Jover, MD, PhD, from Servicio de Medicina Digestiva, Hospital General Universitario Dr Balmis, Instituto de Investigación Biomédica Instituto de Investigación Sanitaria y Biomédica de Alicante, Universidad Miguel Hernández, Alicante, Spain.

We performed a systematic review and meta-analysis with the aim of comparing metachronous colorectal cancer and advanced polyp risk between patients with advanced serrated polyps (a size ≥10 mm or with dysplasia) and those with nonadvanced serrated polyps or normal colonoscopy findings.

We also wanted to assess which specific characteristics of serrated polyps (such as size, dysplasia, location, or multiplicity) were associated with a higher risk of developing metachronous colorectal cancer or advanced polyps.

Serrated polyps are the precursors lesions to around 20% of colorectal cancers and even a higher fraction of postcolonoscopy colorectal cancers. Although vast evidence supports surveillance in individuals with high-risk adenomas, uncertainties remain about which serrated polyps require surveillance and at what intervals, with recommendations adapted from those given to adenomas in the absence of solid evidence. In addition, society guidelines offer varying recommendations with respect to surveillance after resection of multiple or proximal serrated polyps.

Identifying which patients require endoscopic surveillance is key, particularly because postpolypectomy surveillance has become one of the main indications for colonoscopy, with the consequent burden on endoscopy units. Therefore, surveillance colonoscopy should be targeted to individuals who are most likely to benefit, at the minimum frequency required to protect against colorectal cancer.

Our meta-analysis includes 14 studies with over 400,000 patients and a mean follow-up of 4.9 years. Our results show that patients with advanced serrated polyps are at a clinically meaningful higher risk of developing colorectal cancer and advanced polyps than patients with nonadvanced serrated polyps, probably justifying surveillance in this population. This higher risk for metachronous advanced polyps seems to be maintained even in patients with advanced serrated polyps without synchronous adenomas.

In contrast, our analyses did not identify proximal location or multiplicity in serrated polyps as risk factors for higher metachronous colorectal cancer risk over the next 5 years. Therefore, surveillance may not be indicated for these serrated polyps’ features alone.

Our findings also highlight the relative scarcity of evidence on colorectal cancer incidence and mortality and the impact of surveillance in patients with serrated polyps as well as the need for dedicated studies on this topic.

Graphical abstract

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