Post-polypectomy surveillance: walking in the fog

Endoscopic surveillance after premalignant polyp resection is aimed at reducing colorectal cancer (CRC) incidence. Unfortunately, we do not have any well-designed prospective randomized trials evaluating the impact of any of the proposed surveillance strategies on CRC incidence. Available recommendations are based mostly on studies with different designs but with a low level of evidence. In fact, endoscopic surveillance accounts for up to 20 % of the colonoscopies performed, with a limited benefit on CRC reduction when compared with participation in CRC screening programs [1].

“The study by Cross et al. provides additional information on the baseline risk and the effect of different endoscopic surveillance intervals on CRC incidence.”

The design of surveillance strategies is based on two factors: the baseline risk of developing CRC and the effect of the recommended surveillance strategy to reduce this baseline risk. The study by Cross et al. in this issue of Endoscopy provides additional information on the baseline risk and the effect of different endoscopic surveillance intervals on CRC incidence [2]. The authors confirm the low CRC incidence (1.1 %) in the “expanded” low risk group in UK [3] and European Society of Gastrointestinal Endoscopy guidelines [4] irrespective of the surveillance interval. This result confirms that patients meeting these criteria should return to the CRC screening program. On the other hand, the authors have found an increased risk of CRC incidence if surveillance intervals are lengthened in the high risk group of both guidelines, from 1.0 % at a 3-year interval to 2.4 % at a 6-year interval, supporting existing recommendations [3] [4]. However, we must acknowledge some limitations. The majority of the available data are obtained from retrospective studies. As an example, it is not clear why surveillance colonoscopies were scheduled at different intervals, contradicting existing UK recommendations. In fact, the increase in CRC incidence does not have a linear increase, as might be expected. Furthermore, only 34 % of the eligible subjects were included in the analysis owing to incomplete colonoscopy, no surveillance, or unavailable risk classification. Finally, we have to take into account that all baseline colonoscopies were performed before 2010 and 11 % before 2000. Ultimately, these results allow us to keep walking in the fog making decisions under a dim light.

During the past 15 years, two significant changes have modified surveillance strategies. First, CRC screening programs have spread throughout much of the Western world. As a result, the number of subjects with premalignant lesions has increased significantly, reaching up to 2.4 % of the population participating in the first round of a fecal immunochemical test (FIT)-based program [5]. As a result, any recommended surveillance strategy after polyp resection should be compared not with no surveillance but with participation in a CRC screening program. The second great change is the introduction of quality indicators in colonoscopy. The culture of quality improvement in colonoscopy has been embraced by most endoscopists and endoscopy units. As a result, the proportion of colonoscopies with premalignant polyps has increased and, consequently, the risk of CRC during surveillance has been reduced. In light of these changes, the available guidelines have restricted the criteria that define a high risk situation [3] [4]. In fact, the performance of the endoscopist, measured by the adenoma detection rate, is critical in determining the long-term CRC incidence [6]. To date, available guidelines are based only on endoscopic findings and do not consider endoscopists’ quality indicators.

The study by Cross et al. [2], together with other available studies, will contribute to future surveillance strategies. However, further significant change will rely on the findings of randomized controlled trials, which may help to define cases in which endoscopic surveillance is required and the recommended intervals. To this end, the European Polyp Surveillance (EPoS) trials [7], a series of clinical trials comparing different endoscopic surveillance intervals, have completed patient enrollment and will yield information regarding 5-year surveillance in high risk groups by 2025. In addition, the Polyprev trial, a randomized controlled trial comparing endoscopic surveillance with participation in FIT-based CRC screening programs in subjects with high risk lesions detected within a CRC screening program, has just started recruiting patients [8]. Hopefully, the fog will lift, the sun will appear, and we will move forward with a firm step.

Publication History

Article published online:
03 June 2022

• References

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