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No tissue left behind: What can a segmental polyp recurrence rate tell us about quality of polypectomy?

2021; Elsevier BV; Volume: 94; Issue: 2 Linguagem: Inglês

10.1016/j.gie.2021.04.024

1097-6779

Andrew R. Reinink, Aasma Shaukat,

Colorectal Cancer Surgical Treatments

"Don’t call it a comeback, I been here for years"– LL Cool J, “Mama Said Knock You Out” Colonoscopy for colorectal cancer prevention is unique among cancer screening programs. The primary goal is not to find cancer early but to find and remove adenomas before they become malignant, reducing both mortality from colon cancer and morbidity from cancer treatment. Key to this goal, however, is the complete removal of the offending premalignant lesions. This is harder than it may seem. Studies have consistently shown nontrivial rates of incomplete polypectomy,1Pohl H. Srivastava A. Bensen S.P. et al.Incomplete polyp resection during colonoscopy: results of the complete adenoma resection (CARE) study.Gastroenterology. 2013; 144: 74-80.e1Abstract Full Text Full Text PDF PubMed Scopus (452) Google Scholar,2Kim J.S. Lee B.-I. Choi H. et al.Cold snare polypectomy versus cold forceps polypectomy for diminutive and small colorectal polyps: a randomized controlled trial.Gastrointest Endosc. 2015; 81: 741-747Abstract Full Text Full Text PDF PubMed Scopus (106) Google Scholar ≤10.1% of all 5- to 20-mm polyps. This increases with polyp size and piecemeal technique. Circumstantial evidence also suggests that incomplete polypectomy is a major contributor to interval or postcolonoscopy colorectal cancer (PCCRC), including an earlier study from our medical center that reported rates of PCCRC in the same segment where a polypectomy was attempted to be 27% higher than what would be expected by chance alone.3Anderson R. Burr N.E. Valori R. Causes of post-colonoscopy colorectal cancers based on World Endoscopy Organization system of analysis.Gastroenterology. 2020; 158: 1287-1299.e2Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar,4Farrar W.D. Sawhney M.S. Nelson D.B. et al.Colorectal cancers found after a complete colonoscopy.Clin Gastroenterol Hepatol. 2006; 4: 1259-1264Abstract Full Text Full Text PDF PubMed Scopus (256) Google Scholar Thus, complete polypectomy without residual adenoma is a key component of a high-quality colonoscopy and thus an effective colon cancer prevention program. For other components of a high-quality colonoscopy, quality indicators provide feedback that helps both individual physicians and health systems improve.5Valori R. Rey J.-F. Atkin W.S. et al.European guidelines for quality assurance in colorectal cancer screening and diagnosis. First edition--quality assurance in endoscopy in colorectal cancer screening and diagnosis.Endoscopy. 2012; 44: SE88-SE105PubMed Google Scholar Standards exist for adequacy of colon preparation and for cecal intubation rate. For thoroughness of examination we have standards for withdrawal time and adenoma detection rate. For quality of polypectomy, however, there is no widely accepted quality metric that can be tracked. The most germane statistic would be the rate of postcolonoscopy colorectal cancer.6Rutter M.D. Beintaris I. Valori R. et al.World Endoscopy Organization consensus statements on post-colonoscopy and post-imaging colorectal cancer.Gastroenterology. 2018; 155: 909-925.e3Abstract Full Text Full Text PDF PubMed Scopus (96) Google Scholar Although this metric is very important, the long lead time in the adenoma-carcinoma sequence and the overall small numbers of occurrences for each endoscopist mean that it has high variability and cannot provide timely feedback except in the worst cases. This also doesn’t distinguish between different causes of interval cancers: missed adenomas, incomplete resections, or unusually quick de novo adenoma development. With these 3 competing causes of interval neoplasia in mind, Adler et al7Adler J. Toy D. Anderson J.C. et al.Metachronous neoplasias arise in a higher proportion of colon segments from which large polyps were previously removed, and can be used to estimate incomplete resection of 10–20 mm colorectal polyps.Clin Gastroenterol Hepatol. 2019; 17: 2277-2284Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar recently published the first study describing a possible surrogate for polypectomy quality. Their analysis rested on the assumption that the rates of de novo adenoma formation and of missed adenomas would be constant throughout the colon, but the rate of adenoma due to incomplete polypectomy would be applicable only to segments of colon in which an adenoma was resected. They analyzed the records of 1031 patients (6186 colon segments) who underwent both a baseline colonoscopy with resection of at least one 10- to 20-mm adenomatous polyp and a follow-up colonoscopy 6 months to 5 years later. They were able to calculate the overall rates of adenomatous polyps found in colonic segments from which a previous adenoma had or had not been resected. The difference in those numbers thus became the likelihood of finding a polyp resulting from a previous incomplete resection. Their results were intriguing. Segments from which a single 10- to 20-mm adenoma had been resected had a 13% absolute increase in detection of subsequent adenomas: a 2.64-fold increase. This figure seemed to vary appropriately in concert with known risk factors for incomplete polypectomy, increased to 18.3% when only nonpedunculated polyps were included, to 22.2% when segments with multiple polyps were included, and to 28.4% in segments with initial >20-mm polyps. In the 10- to 20-mm group, piecemeal resection also substantially increased the incomplete polypectomy rate∖to 28%. Overall, the authors calculated an incomplete resection rate of 18% for nonpedunculated 10- to 20-mm polyps, very similar to the rate of 17% for these polyps from the CARE study, which was based on a completely different methodology using contemporaneous biopsy specimens. Although the article by Adler et al7Adler J. Toy D. Anderson J.C. et al.Metachronous neoplasias arise in a higher proportion of colon segments from which large polyps were previously removed, and can be used to estimate incomplete resection of 10–20 mm colorectal polyps.Clin Gastroenterol Hepatol. 2019; 17: 2277-2284Abstract Full Text Full Text PDF PubMed Scopus (20) Google Scholar focused on 10- to 20-mm polyps, the authors did note that the principle held with smaller polyps—segments with any number of 20 mm, multiple large polyps, or sessile serrated adenomas), the key findings are quite comparable, including a SMAR-IR of 11.4% in segments with previous 10- to 20-mm polyps and 13.2% in segments with a previous 6- to 9-mm polyp. The authors advance the analysis in 2 further ways as well. First, they examined the rates of metachronous advanced adenomas (as opposed to all adenomas) and again found marked increases in segments where previous adenomas had been resected. Second, they were able to calculate SMAR-IR for each of the 6 endoscopists performing the index colonoscopies, which ranged from 7% to 15.5% (for a composite group of 6- to 20-mm polyps). The authors acknowledge several limitations, most notably the question whether one of their underlying assumptions is correct: whether the intrasubject rates of de novo adenoma formation and growth are constant between colonic segments. If there is a “field effect” where certain segments of a given subject’s colon are more likely to form adenomas, the estimate of the percentage of adenomas that are due to incomplete resection would be falsely elevated. However, given a large enough sample size, this confounding factor should apply evenly across endoscopists, allowing SMAR-IR to retain utility as a quality measure. A few other limitations to the current study preclude drawing strong conclusions from this data. First, the sample size for this kind of analysis is rather small. Second, colonoscopies are also not independent observations but rather are clustered by the endoscopist, which further reduces power and would ideally be analyzed with hierarchic modeling. Third, there are practical considerations that make the proposed use of SMAR-IR as an endoscopist-level quality metric challenging. Necessary criteria for a good quality indicator include that it should be calculated at the level of the endoscopist, be variable, be readily measurable, and be actionable.9Rutter M.D. Senore C. Bisschops R. et al.The European Society of Gastrointestinal Endoscopy Quality Improvement Initiative: developing performance measures.Endoscopy. 2016; 48: 81-89PubMed Google Scholar With only 6 initial endoscopists (with small numbers of colonoscopies per endoscopist) it is difficult to assess and understand the variability of SMAR-IR from this study. Further, the authors used a generous follow-up interval of 6 months to 10 years for follow-up of 6- to 9 mm polyps, and 6 months to 5 years for polyps 10 to 20 mm. This range itself is long enough that biologic factors affecting the growth of new lesions along with patient factors such as age, geography, and lifestyle risk factors may have more impact on SMAR than the initial endoscopist. A time-to-event analysis accounting for exposure time may help in future studies, as well as matching patients for age categories and other risk factors that confer different risks of SMAR. Finally, it is unclear whether SMAR-IR would be a low-quality indicator for the endoscopist who performed the initial examination or would reflect more the high quality of the endoscopist performing the surveillance examination. Both are factors in determining SMAR. Even if the same endoscopist were to perform both examinations, with changes in technology, technique, and preparation quality, the findings may not be stable or reliable indicators of future risk. For this study, the initial colonoscopies took place between 2006 and potentially as late as 2017—a period that saw the transition from standard-definition to high-definition endoscopy and on standards of care in polyp resection. Future secular trends in endoscopic technology and procedures are likely to have significant impacts on adenoma detection rate and resection completeness as well, making comparisons across time such as SMAR-IR difficult.10Shaukat A. Holub J. Greenwald D. et al.Variation over time and factors associated with detection rates of sessile serrated lesion across the United States: results form a national sample using the GIQuIC registry.Am J Gastroenterol. 2021; 116: 95-99Crossref PubMed Scopus (6) Google Scholar As a potential quality indicator, SMAR-IR has both promise and obstacles. This leads to some obvious next questions: What would a better quality indicator for completeness of resection look like? And what form would a program for measuring, benchmarking, and improving polypectomy competence take? Future directions may require developing and validating standardized tools, such as the Direct Observation of Polypectomy Skills (DOPyS),11Duloy A.M. Kaltenbach T.R. Wood M. et al.Colon polypectomy report card improves polypectomy competency: results of a prospective quality improvement study (with video).Gastrointest Endosc. 2019; 89: 1212-1221Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar routine auditing and feedback for endoscopists by trained experts, and further research linking these quality efforts to reduction in PCCRC. Our European colleagues are ahead of the curve in these efforts.9Rutter M.D. Senore C. Bisschops R. et al.The European Society of Gastrointestinal Endoscopy Quality Improvement Initiative: developing performance measures.Endoscopy. 2016; 48: 81-89PubMed Google Scholar Their progress is making it abundantly clear that improving polypectomy completeness to decrease PCCRC will be a major area of focus in the near future. As our ability to detect and resect polyps improves, perhaps we will truly be able to say that a polyp found on surveillance colonoscopy has not “been there for years.” All authors disclosed no financial relationships. Segmental metachronous adenoma rate as a metric for monitoring incomplete resection in a colonoscopy screening programGastrointestinal EndoscopyVol. 94Issue 2PreviewPolypectomy technique has been shown to vary among colonoscopists, and interval colorectal cancer may result from incomplete resection of an adenoma. Methods to monitor polypectomy quality and the size of polyps resected to monitor have not been well defined. The aim of this study was to compare the rate of metachronous adenoma attributable to incomplete resection in polyps 6 to 9 mm versus polyps 10 to 20 mm. Full-Text PDF