Improving Detection of Sessile Polyps

Educational Objectives

The goal of this program is to improve the detection of sessile serrated polyps (SSPs). After hearing and assimilating this program, the clinician will be better able to:

1. Evaluate specific colonoscopy techniques and strategies to improve detection rates of SSPs.
2. Analyze evidence-based strategies for improving adenoma detection rate.

Summary

Introduction: 5% to 8% of colorectal cancers are interval cancers, detected within 3 to 5 yr of a negative colonoscopy; this rate has increased in women, older patients, those with a family history of colon cancer, comorbidities (eg, inflammatory bowel disease, diverticulosis), and is influenced by the endoscopist's skill; miss rates are 27% for polyps <5 mm, 13% for polyps 6 to 9 mmm, and 6% for polyps >1 cm

Pathology: hyperplastic polyps are common in the sigmoid colon and rectum and are benign; they have a serrated tooth-like appearance and are the most common sessile polyps; tubular adenomas have a round profile, while villous adenomas, often larger and sessile, are difficult to detect and remove; tubular villous adenomas show a mixed pattern; serrated adenomas are categorized into sessile serrated adenomas (SSA) and traditional serrated adenomas; SSAs are more common in older women and often on the right side, have precancerous potential, grow faster than typical adenomas, and are difficult to identify because of their flat, pale, and ill-defined appearance

Note: typical adenoma-to-cancer progression differs from that of sessile serrated polyps (SSPs); SSPs involve different gene mutations (BRAF, KRAS) affecting cell growth and significant promoter hypermethylation, leading to gene silencing and faster tumor formation (3-5 yr) compared with typical adenomas (≥10 yr); SSPs are hard to detect because of their large size, ill-defined borders, and flat and pale appearance, sometimes with a cloudy surface or fecal debris rims

Adenoma detection rate (ADR): the proportion of screening colonoscopies with ≥1 adenoma (average 25%-30%, higher in men); higher ADR is associated with a lower risk for interval colon cancer and mortality; Corley et al (2014) — showed that endoscopists in the highest ADR quintile had 50% the interval cancer risk and 33% the colon cancer mortality of those in the lowest quintile; each 1% increase in ADR reduces interval cancer risk by 3%; Kaminski et al (2017) — demonstrated that providing annual feedback and quality benchmark indicators to 294 endoscopists over 5 yr significantly improved ADR; initially, the lowest-performing group comprised 30% of the endoscopists, but this decreased to 10% by the fifth year; the highest-performing group’s representation increased from 8% to 31% over the same period

Identification of flat polyps: the initial and fundamental requirement is a high-quality bowel preparation; the presence of stool can obscure the visibility of polyps, making their detection challenging; utilizing a bowel preparation scale, eg, the Boston Bowel Preparation Scale, which assesses the cleanliness of the right, transverse, and left colon in 3 segments (scoring from 0 [worst] to 3 [best]), is useful

Withdrawal time: Barclay et al (2006) suggested a minimum withdrawal time of 6 min, excluding cleaning and polypectomy procedures; recent evidence suggest that endoscopists with withdrawal times >6 min demonstrate significantly higher ADR, ≈4 times greater than those with faster withdrawal times; some studies even propose extending this withdrawal time to 8 to 10 min for improved detection

Right colon: a significant number of missed polyps are located in the right colon; dedicating more time to examining this region is beneficial; a common practice involves obtaining ≥2 different views of the right colon, through a forward view or a retroflexed view; both techniques have demonstrated significant improvements in ADR; a second forward view increases ADR in the right colon by 8%, and retroflexion has shown similar success rates, achievable in 91% to 93% of patients; a practical strategy involves examining the right colon twice with a forward view, emphasizing a slow and meticulous inspection as if viewing it for the first time to identify any potentially overlooked lesions; time-intensive techniques, eg, chromoendoscopy, may help in polyp detection

Dye-based chromoendoscopy: utilizes stains, eg, methylene blue, an absorptive stain where normal cells absorb the blue color while dysplastic cells do not, allowing for targeted biopsies of unstained areas; indigo carmine is a contrast stain that pools in mucosal crevices, enhancing the visualization of polyp boundaries

Narrow band imaging (NBI): filters optical white light into blue and green wavelengths, improving the visualization of colonic margins and potentially aiding in histologic assessment; under NBI, features, eg, reddish mucus cap, with magnification, varicose microvascular vessels, blackish pits indicative of expanded surface crypts, can be observed

Endoscopes: advancements in endoscopic technology have increased the detection of serrated lesions by 2.5%; the Fuse endoscope has 3 cameras providing a panoramic 330-degree view; the Third Eye Retroscope offers a retrograde backward view to improve visualization; the multi-monitor setup associated with these advanced endoscopes may be distracting; the G-EYE colonoscopy system features an integrated, reusable balloon at its tip; when inflated, this balloon flattens colonic folds and reduces slippage, thereby enhancing visualization; similar benefits of fold flattening and improved visualization can also be achieved using disposable distal attachments, eg, stasis cap, Olympus eyecup vision, EndoRing; these devices do incur additional costs

Artificial intelligence (AI): computer-aided detection (CAD) systems use AI to highlight polyps in real time on the monitor; evidence suggests an improvement in ADR with AI, particularly for very small polyps; AI-assisted detection may influence the timing of subsequent procedures for identified precancerous polyps

Evidence: in a meta-analysis, Mohan et al (2020) demonstrated that CAD resulted in a 50% relative decrease in the adenoma miss rate and a 24% relative increase in the ADR; several CAD systems are available; evidence suggests the MAGNETIQ EYE is effective in identifying lesions in the right colon, even those measuring 6 to 9 mm; Maas et al (2024) employed a tandem colonoscopy design, revealing a polyp miss rate of 19% when CAD was used as the initial colonoscopy; limitations include cost, a potential slight increase in withdrawal time (20 sec), potential complications associated with increased polypectomy, the continued necessity of good bowel preparation, and the requirement for purposeful visual inspection

Readings

Barclay RL, Vicari JJ, Doughty AS, et al. Colonoscopic withdrawal times and adenoma detection during screening colonoscopy. N Engl J Med. 2006;355(24):2533-2541. doi:10.1056/NEJMoa055498; Corley DA, Jensen CD, Marks AR, et al. Adenoma detection rate and risk of colorectal cancer and death. N Engl J Med. 2014;370(14):1298-1306. doi:10.1056/NEJMoa1309086; Haghbin H, Zakirkhodjaev N, Beran A, et al. G-EYE improves polyp, adenoma, and serrated polyp detection rates in colonoscopy: a systematic review and meta-analysis. J Clin Gastroenterol. 2024;58(7):668-673. Published 2024 Aug 1. doi:10.1097/MCG.0000000000001924; Kalady MF. Sessile serrated polyps: an important route to colorectal cancer. J Natl Compr Canc Netw. 2013;11(12):1585-1594. doi:10.6004/jnccn.2013.0182; Kamal F, Khan MA, Lee-Smith W, et al. Second exam of right colon improves adenoma detection rate: systematic review and meta-analysis of randomized controlled trials. Endosc Int Open. 2022;10(10):E1391-E1398. Published 2022 Oct 17. doi:10.1055/a-1896-4499; Kaminski MF, Wieszczy P, Rupinski M, et al. Increased rate of adenoma detection associates with reduced risk of colorectal cancer and death. Gastroenterology. 2017;153(1):98-105. doi:10.1053/j.gastro.2017.04.006; Maas MHJ, Neumann H, Shirin H, et al. A computer-aided polyp detection system in screening and surveillance colonoscopy: an international, multicentre, randomised, tandem trial. Lancet Digit Health. 2024;6(3):e157-e165. doi:10.1016/S2589-7500(23)00242-X; Mohan BP, Facciorusso A, Khan SR, et al. Real-time computer aided colonoscopy versus standard colonoscopy for improving adenoma detection rate: a meta-analysis of randomized-controlled trials. EClinicalMedicine. 2020;29-30:100622. Published 2020 Nov 21. doi:10.1016/j.eclinm.2020.100622.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Lo was recorded at What’s New in GI 2024, held on April 20, 2024, in Dallas, TX, and presented by University of Texas Southwestern Medical Center. For information on upcoming CME activities from this presenter, please visit utsouthwestern.edu. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.50 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.50 CE contact hours.

Lecture ID:

GE390902

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.