Postpolypectomy surveillance in patients with adenomas and serrated lesions: a proposal for risk stratification in the context of organized colorectal cancer-screening programs

In the past few years, a tremendous effort has been made by scientific societies, cooperative groups, and public institutions to rationalize colorectal cancer (CRC) screening and surveillance strategies, with the final goal of improving both effectiveness and efficiency of such strategies [1] [2] [3]. Although the European Guidelines [4] have represented a landmark toward the standardization of policies across Europe, their surveillance strategies have been focused mainly on conventional adenomas [4]. This drawback has recently been addressed by two expert groups, which have proposed two different postpolypectomy surveillance strategies for patients with serrated polyps [5] [6].

When the Catalan CRC Screening Program decided to adopt the surveillance strategy endorsed by the European Guidelines, we faced two issues: first, which strategy to use in patients with serrated polyps and how to adapt it to the overall European policy; second, how to deal with those individuals with both adenomas and serrated lesions. After reviewing the literature and extensive debate, we achieved a consensus agreement ([Table 1]).

Table 1 Proposal for risk stratification of patients with colorectal adenomas and/or serrated polyps[1] detected at screening colonoscopy, and postpolypectomy surveillance strategies in the context of organized colorectal cancer-screening programs.

Risk stratum	Diagnostic criteria[2]	Surveillance strategy
No-risk lesions	Hyperplastic polyps < 10 mm limited to rectum and sigmoid colon	Return to the screening program
Low-risk lesions[3]	1 – 2 tubular adenomas < 10 mm with low-grade dysplasia, or 1 – 2 serrated polyps < 10 mm without dysplasia[4] [5]	Return to the screening program
Intermediate-risk lesions[6]	3 – 4 tubular adenomas < 10 mm with low-grade dysplasia, or 1 – 4 tubular adenomas 10 – 19 mm with low-grade dysplasia, or 1 – 4 adenomas < 20 mm with villous component, and/or high-grade dysplasia, and/or intramucosal carcinoma, or 3 – 4 serrated polyps < 10 mm without dysplasia[4] [5], or 1 – 4 serrated polyps 10 – 19 mm without dysplasia[4] [5], or 1 – 4 serrated polyps < 20 mm with dysplasia[4] [5]	Colonoscopy at 3 years
High-risk lesions	≥ 5 adenomas/serrated polyps[4], or  ≥ 1 adenoma/serrated polyp[4] ≥ 20 mm	Colonoscopy at 1 year[7]

¹ Serrated polyps include hyperplastic polyps, serrated sessile adenomas, traditional serrated adenomas, and mixed polyps.

² Patients are classified according to the highest-risk detected lesion. In case of both adenomas and serrated polyps being present and classified at the same risk stratum, the total number of lesions must be considered (see footnotes ³ and ⁶).

³ When both adenomas and serrated polyps coexist in one patient at the same examination and total 3 or 4 lesions, they are upgraded to intermediate-risk lesions.

⁴ Excluding hyperplastic polyps < 10 mm located at rectum and sigmoid colon.

⁵ Traditional serrated adenomas and mixed polyps are considered dysplastic.

⁶ When both adenomas and serrated polyps coexist in one patient at the same examination and total ≥ 5 lesions, they are upgraded to high-risk lesions.

⁷ Clearing colonoscopy to check for missed lesions.

With respect to the surveillance strategy for patients with serrated polyps, we opted for the guidelines issued by the European Society of Gastrointestinal Endoscopy (ESGE) [6]. However, in order to reconcile these recommendations with the three-group European approach, we decided to use the same size and number cutoff suggested in the latter to reclassify these patients ([Table 1]). Whereas the recommended surveillance strategies for low- and intermediate-risk patients are the same as those proposed by the ESGE [6], high-risk patients are submitted to a clearing colonoscopy at 1 year in concordance with the European Guidelines for patients with adenoma [4]. The rationale for such a modification relies on the higher prevalence of missed lesions in patients with a large number of polyps, and the higher probability of residual tissue after endoscopic polypectomy of large lesions, situations that are both more frequent and relevant in the context of serrated lesions [5].

For patients with both adenomas and serrated polyps identified during the same examination, we have adopted a similar pragmatic approach, which takes into consideration the total number of lesions, consistent with the European policy ([Table 1]). This proposal is based on two assumptions. First, tubular adenomas with low-grade dysplasia have a similar risk to serrated polyps without dysplasia, whereas adenomas with villous component or high-grade dysplasia have a similar behavior to serrated polyps with dysplasia. Second, the risk for metachronous lesions depends on the most advanced lesion but, in cases where both adenomas and serrated polyps coexist at the same risk stratum, the final risk depends on the total number of lesions.

We are aware of the limitations of our proposal, which stems from the scarcity of scientific evidence on postpolypectomy surveillance. However, it is also obvious that it is necessary to establish clear, sound, and easy-to-follow recommendations for the large proportion of participants in organized CRC screening programs in whom neoplastic lesions are diagnosed. This is especially relevant because most of these individuals are removed from the screening programs and followed in different and heterogeneous clinical settings [4] [7]. We hope our proposal may contribute to solving this critical issue or, at least, to stimulate the debate in such a relevant topic.

^* on behalf of the Catalan Colorectal Cancer Screening Program Expert Panel on Colonoscopy Surveillance. Members of the Catalan Colorectal Cancer Screening Program Expert Panel on Colonoscopy Surveillance: Antoni Castells (Co-chair), Montserrat Andreu (Co-chair), Gemma Binefa, Anna Fité, Rebeca Font, Josep A. Espinàs, Francesc Balaguer, Xavier Bessa, María López-Cerón, Leticia Moreira, Maria Pellisé, Francisco Rodríguez-Moranta, Àngels Pozo, and Anna Serradesanferm.

• References

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