Proximal serrated polyp detection rate and post-colonoscopy colorectal cancer: the missing link

Colorectal cancer (CRC) is among the most prevalent forms of cancer worldwide and is responsible for a substantial proportion of cancer-related deaths [1]. Colonoscopy with polypectomy of all relevant lesions is vital for the prevention of CRC. Unfortunately, up to 8 % of all CRCs occur after colonoscopy, also demonstrating its limitations [2]. The literature shows that the majority of these so-called post-colonoscopy CRCs (PCCRCs) are due to missed or incompletely resected lesions [3]. Therefore, improving colonoscopy quality seems key to decreasing the incidence of PCCRC.

“Therefore, it seems logical to recommend that screening organizations should enable the systematic measurement of both the PSPDR and ADR of individual endoscopists.”

To enable monitoring of colonoscopy quality, several indicators have been studied, of which the adenoma detection rate (ADR) of individual endoscopists is the most well established. Several studies have demonstrated a negative association between ADR of an endoscopist and the occurrence of PCCRC, both in primary colonoscopy and in fecal immunochemical test (FIT)-based screening cohorts [4]. While ADR is both reliable and easy to measure, it also has its boundaries. One of the major restrictions is the fact that serrated polyps are not taken into account when measuring the ADR. Up to 30 % of CRCs occur from serrated polyps and serrated polyps are overrepresented as precursors of PCCRC [5]. The main issue is that the endoscopic appearance of serrated polyps is very discrete, and as a result, these lesions are often missed or incompletely resected during colonoscopy [6]. The proximal serrated polyp detection rate (PSPDR) was recently proposed as an additional quality para-meter to specifically monitor endoscopist quality in the detection of serrated polyps. This parameter seems preferable over the serrated polyp detection rate as innocuous hyperplastic polyps in the rectosigmoid are not taken into account, and preferable over the sessile serrated lesion detection rate, as the PSPDR is not biased by the interobserver variation among pathologists in the recognition of sessile serrated lesions. In a recent study, the PSPDR was demonstrated to be negatively associated with the occurrence of PCCRC within a FIT-based screening cohort. Furthermore, patients treated by endoscopists with a high ADR and PSPDR were shown to have the lowest risk of CRC, which supports the incremental value of the PSPDR alongside the ADR [7].

In this issue of Endoscopy, Zessner-Spitzenberg et al. report new evidence for the use of the PSPDR as a quality parameter [8]. The authors evaluated the association between the PSPDR as well as the ADR and PCCRC mortality within the Austrian primary colonoscopy population screening program using a Cox proportional hazard model. In total, 229 729 colonoscopies performed by 308 endoscopists were included for analysis. Both PSPDR (3 percentage point decrease of PCCRC-related death per 1 percentage point increase of PSPDR) and ADR (2 percentage point decrease of PCCRC-related death per 1 percentage point increase of ADR) were negatively associated with PCCRC mortality. ADR and PSPDR were moderately correlated with a Spearman rank coefficient of 0.7. Using linear regression, a PSPDR value of 11.1 % was identified as corresponding to an ADR of 25 % (the current performance target recommended by the European Society of Gastrointestinal Endoscopy). In total, 27.9 % of endoscopists exceeded both performance cutoffs. Individuals treated by these endoscopists had the lowest risk of PCCRC-related death. Accordingly, the authors state that a sufficiently high ADR and PSPDR might be necessary to assure long-term PCCRC risk reduction.

The results of this study are of incremental value to enable further improvement of colonoscopy quality. Not only is this the first study to show the negative association between PSPDR and PCCRC in primary colonoscopy screening, it is also the first to demonstrate a negative effect on PCCRC mortality. Furthermore, this study serves as external validation for the PSPDR as a quality indicator as a whole, as now two independent studies have demonstrated the added value of the PSPDR besides the ADR for monitoring colonoscopy quality of individual endoscopists [7] [8]. Therefore, it seems logical to recommend that screening organizations should enable the systematic measurement of both the PSPDR and ADR of individual endoscopists. Furthermore, training programs should be set up to improve PSPDR of low detectors to decrease the incidence of PCCRC.

Publikationsverlauf

Artikel online veröffentlicht:
26. Januar 2023

• References

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