Current Approaches in Managing Colonic Serrated Polyps and Serrated Polyposis.

For decades, conventional adenomas were the only known precursor lesions of colorectal cancer (CRC). Accordingly, education and research regarding CRC prevention were mainly focused on adenomas. The groundbreaking discovery that serrated polyps (SPs) also have the potential to develop into CRCs, and seem to account for a considerable proportion of sporadic CRCs, has led to a paradigm shift in the prevention, diagnosis, and treatment of CRC. Studies in recent years have led to our current understanding of SPs and associated CRC, but a lot of work is still to be done to further improve knowledge about this serrated neoplasia pathway and the clinical management of SPs and serrated polyposis syndrome (SPS). In this review, we reflect on the current understanding of SPs with respect to terminology, detection, resection, and surveillance and reflect on the management of SPS.

Effect of an E-learning resource on endoscopists' proximal serrated polyp detection rate: a randomized controlled trial.

BACKGROUND: Recent studies demonstrated that a higher proximal serrated polyp detection rate (PSPDR) among endoscopists is associated with a lower risk of post-colonoscopy colorectal cancer (PCCRC) incidence and death for their patients. Our objective was to evaluate the effect of an e-learning resource on PSPDR. METHODS: We performed a multicenter randomized controlled trial within the Dutch fecal immunochemical test-based colorectal cancer screening program. Endoscopists were randomized using block randomization per center to either receive a 60-minute e-learning resource on serrated polyp detection or not. PSPDR was calculated based on all colonoscopies performed during a 27-month pre-intervention and a 17-month post-intervention period. The primary end point was difference in PSPDR between intervention and control arms (intention to treat) using mixed effect logistic regression modeling, with time (pre-intervention/post-intervention) and interaction between time and arm (intervention/control) as fixed effects, and endoscopists as random effects. RESULTS: 116 endoscopists (57 intervention, 59 controls) were included, and performed 27494 and 33888 colonoscopies, respectively. Median PSPDR pre-intervention was 13.6% (95%CI 13.0-14.1) in the intervention arm and 13.8% (95%CI 13.3-14.3) in controls. Post-intervention PSPDR was significantly higher over time in the intervention arm than in controls (17.1% vs. 15.4%, P=0.01). CONCLUSION: In an era of increased awareness and increasing PSPDRs, endoscopists who undertook a one-time e-learning course significantly accelerated the increase in PSPDR compared with endoscopists who did not undertake the e-learning. Widespread implementation might reduce PCCRC incidence.

Appendiceal lesions in serrated polyposis patients are easily overlooked but only seldomly lead to colorectal cancer.

BACKGROUND: Serrated polyposis syndrome (SPS) is the most prevalent colonic polyposis syndrome and is associated with an increased colorectal cancer risk. A recent study in resected appendices of SPS patients reported that 6/23 (26.1 %) of identified serrated polyps had histological dysplasia. We evaluated the prevalence and clinical relevance of appendiceal lesions in a large SPS cohort. METHODS: Prospective data from 2007 to 2020 for a cohort of 199 SPS patients were analyzed. Data were retrieved from endoscopy and pathology reports. Patients who underwent (pre)clearance colonoscopies, surveillance colonoscopies, or colorectal surgery including the appendix were separately evaluated for the presence of appendiceal lesions. The primary outcome was the prevalence of adenocarcinomas and serrated polyps/adenomas with advanced histology in the surgery group. RESULTS: 171 patients were included, of whom 110 received endoscopic surveillance and 34 underwent surgery. Appendiceal lesion prevalence in the surgery group was 14 /34 (41.2 %, 95 %CI 24.7 %-59.3 %); none were advanced on histology. Detection rates in the (pre)clearance group were 1 /171 (0.6 %, 95 %CI 0.01 %-3.2 %) for advanced and 3 /171 (1.8 %, 95 %CI 0.04 %-5.0 %) for nonadvanced appendiceal lesions, all of which were sessile serrated lesions. During 522 patient-years of surveillance, no advanced appendiceal lesions were detected at endoscopy, and in 1 /110 patients (0.9 %, 95 %CI 0.02 %-5.0 %) was a nonadvanced lesion detected. CONCLUSION: Appendiceal lesions are common in SPS patients. The discrepancy between the endoscopic detection rate of appendiceal lesions and the reported prevalence in surgically resected appendices suggests a substantial miss-rate of appendiceal lesions during colonoscopy. Advanced appendiceal lesions are however rare and no appendiceal adenocarcinomas occurred, implying limited clinical relevance of these lesions.

Advanced serrated polyps as a target of screening: detection rate and positive predictive value within a fecal immunochemical test-based colorectal cancer screening population.

BACKGROUND : Advanced serrated polyps (ASPs) have a comparable risk to advanced adenomas for progression to colorectal cancer (CRC). The yield of most CRC screening programs, however, is based on advanced adenomas and CRC only. We assessed the ASP detection rate, and positive predictive value (PPV) including ASPs in a fecal immunochemical test (FIT)-based screening program. METHODS : We analyzed the findings of follow-up colonoscopies of FIT-positive screenees in the Dutch CRC screening program from 2014 until 2020. Data were retrieved from the national screening and pathology database. An ASP was defined as any serrated polyp of ≥ 10 mm, sessile serrated lesion with dysplasia, or traditional serrated adenoma. The ASP detection rate was defined as the proportion of colonoscopies with ≥ 1 ASP. PPV was originally defined as the proportion of individuals with a CRC or advanced adenoma. The updated PPV definition included CRCs, advanced adenomas, and/or ASPs. RESULTS : 322 882 colonoscopies were included in the analyses. The overall detection rate of ASPs was 5.9 %. ASPs were detected more often in women than men (6.3 % vs. 5.6 %; P < 0.001). ASP detection rates in individuals aged 55-59, 60-64, 65-69, and 70 + were 5.2 %, 6.1 %, 6.1 %, and 5.9 %, respectively (P < 0.001). The PPV for CRCs and advanced adenomas was 41.1 % and increased to 43.8 % when including ASPs. The PPV increase was larger in women than in men (3.2 vs. 2.4 percentage points). CONCLUSIONS : 5.9 % of FIT-positive screenees had ASPs, but half of these were detected in combination with a CRC or advanced adenoma. Therefore, including ASPs results in a small increase in the yield of FIT-based screening.

Polyps and Colorectal Cancer in Serrated Polyposis Syndrome: Contribution of the Classical Adenoma-Carcinoma and Serrated Neoplasia Pathways.

INTRODUCTION: Patients with serrated polyposis syndrome (SPS) have an increased risk to develop colorectal cancer (CRC). Due to an abundance of serrated polyps, these CRCs are assumed to arise mainly through the serrated neoplasia pathway rather than through the classical adenoma-carcinoma pathway. We aimed to evaluate the pathogenetic routes of CRCs in patients with SPS. METHODS: We collected endoscopy and pathology data on CRCs and polyps of patients with SPS under treatment in our center. Our primary end point was the proportion of BRAFV600E mutated CRCs, indicating serrated pathway CRCs (sCRCs). CRCs lacking BRAFV600E most likely inferred a classical adenoma-carcinoma origin (aCRCs). We assessed patient, polyp, and CRC characteristics and stratified for BRAFV600E mutation status. RESULTS: Thirty-five patients with SPS harbored a total of 43 CRCs. Twenty-one CRCs (48.8%) carried a BRAFV600E mutation, 10 of which lacked MLH1 staining and 17 (81%) were located in the proximal colon. Twenty-two CRCs (51.1%) did not carry a BRAFV600E mutation and were MLH1 proficient. Of these 22 putatively aCRCs, 17 (77.3%) were located distally and one-third (36.4%) harbored a pathogenic KRAS or NRAS mutation. In patients with BRAFwt -CRCs, a higher ratio of the median number of conventional adenomas versus serrated polyps was found (4 vs 13) than patients with BRAFV600E -CRCs (1 vs 14). DISCUSSION: Our study indicates that in patients with SPS, the ratio of sCRCs:aCRCs on average is 50:50. This elevated sCRC:aCRC ratio in patients with SPS, when compared with non-SPS patients, correlates well with the differences in the ratios of the numbers of sessile serrated lesions and conventional adenomas in patients with SPS and non-SPS patients, respectively.

Serrated polyp detection and risk of interval post-colonoscopy colorectal cancer: a population-based study.

BACKGROUND: Adenoma detection rate (ADR) is a well-established quality indicator for colonoscopy and is inversely associated with the incidence of interval post-colonoscopy colorectal cancer. However, interval post-colonoscopy colorectal cancers frequently develop from serrated polyps, which are not included in the ADR. Therefore, the proximal serrated polyp detection rate (PSPDR) has been proposed as a quality indicator, but its association with interval post-colonoscopy colorectal cancer has not been studied. We aimed to evaluate this potential association based on data collected in the Dutch colorectal cancer screening programme. METHODS: In this population-based study, using colonoscopy data from the Dutch faecal immunochemical test-based colorectal cancer screening programme and cancer data from the Netherlands Cancer Registry, we evaluated the association between endoscopists' individual PSPDR and their patients' risk of interval post-colonoscopy colorectal cancer with a shared frailty Cox proportional-hazard regression analysis. Participants in the screening programme who were eligible for inclusion were aged 55-76 years, had a positive faecal immunochemical test (cutoff 15 µg Hb/g faeces at start and changed mid-2014 to 47 µg Hb/g faeces), were asymptomatic, and underwent a colonoscopy between Jan 1, 2014, and Dec 31, 2020. The PSPDR was defined as the proportion of colonoscopies in which at least one serrated polyp proximal to the descending colon was detected, confirmed by histopathology. The ADR was defined as the proportion of all colonoscopies in which at least one conventional adenoma was detected, confirmed by histopathology. Detection rates were determined for each endoscopist individually. We additionally evaluated the risk of interval post-colonoscopy colorectal cancer for endoscopists with a PSPDR and ADR above the median versus endoscopists with either one or both parameters below the median. This study is registered with the Netherlands Trial Registry, NL8350. FINDINGS: During the study period, 329 104 colonoscopies were done, of which 277 555, done by 441 endoscopists, were included in the PSPDR calculations. The median PSPDR was 11·9% (IQR 8·3-15·8) and median ADR was 66·3% (61·4-69·9). The correlation between the PSDPR and ADR was moderate (r=0·59; p<0·0001). During a median follow-up of 33 months (IQR 21-42), 305 interval post-colonoscopy colorectal cancers were detected. For each percentage point increase in PSPDR, the adjusted interval post-colonoscopy colorectal cancer hazard was 7% lower (hazard ratio [HR] 0·93, 95% CI 0·90-0·95; p<0·0001). Compared with endoscopists with a PSPDR greater than 11·9% and ADR greater than 66·3%, the HR of interval post-colonoscopy colorectal cancer for endoscopists with a low PSPDR and high ADR was 1·79 (95% CI 1·22-2·63), for endoscopists with a high PSPDR and low ADR was 1·97 (1·19-3·24), and for endoscopists with a low PSPDR and low ADR was 2·55 (1·89-3·45). INTERPRETATION: The PSPDR of an endoscopist is inversely associated with the incidence of interval post-colonoscopy colorectal cancer. Implementation of PSPDR monitoring, in addition to ADR monitoring, could optimise colorectal cancer prevention. FUNDING: None.