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Risk of Colorectal Neoplasia After Removal of Conventional Adenomas and Serrated Polyps
abstract
This abstract is available on the publisher's site.
Access this abstract nowBACKGROUND
Surveillance colonoscopy after polyp removal is recommended to prevent subsequent colorectal cancer (CRC). It is known that advanced adenomas have a substantially higher risk than non-advanced ones, but optimal intervals for surveillance remain unclear.
DESIGN
We prospectively followed 156 699 participants who had undergone a colonoscopy from 2007 to 2017 in a large integrated healthcare system. Using multivariable Cox proportional hazards regression we estimated the subsequent risk of CRC and high-risk polyps, respectively, according to index colonoscopy polyps, colonoscopy quality measures, patient characteristics and the use of surveillance colonoscopy.
RESULTS
After a median follow-up of 5.3 years, we documented 309 CRC and 3053 high-risk polyp cases. Compared with participants with no polyps at index colonoscopy, those with high-risk adenomas and high-risk serrated polyps had a consistently higher risk of CRC during follow-up, with the highest risk observed at 3 years after polypectomy (multivariable HR 5.44 (95% CI 3.56 to 8.29) and 8.35 (95% CI 4.20 to 16.59), respectively). Recurrence of high-risk polyps showed a similar risk distribution. The use of surveillance colonoscopy was associated with lower risk of CRC, with an HR of 0.61 (95% CI 0.39 to 0.98) among patients with high-risk polyps and 0.57 (95% CI 0.35 to 0.92) among low-risk polyps. Among 1548 patients who had high-risk polyps at both index and surveillance colonoscopies, 65% had their index polyps in the proximal colon and 30% had index and interval polyps in the same segments.
CONCLUSION
Patients with high-risk polyp findings were at higher risk of subsequent CRC and high-risk polyps and may benefit from early surveillance within 3 years. The subsite distribution of the index and recurrent high-risk polyps suggests the contribution of incomplete resection and missed lesions to the development of interval neoplasia.
Additional Info
Disclosure statements are available on the authors' profiles:
Risk of colorectal neoplasia after removal of conventional adenomas and serrated polyps: a comprehensive evaluation of risk factors and surveillance use
Gut 2024 Jun 05;[EPub Ahead of Print], G Polychronidis, MM He, M Vithayathil, MD Knudsen, K Wang, M SongFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Most clinical guidelines recommend screening colonoscopy beginning somewhere between 45 and 50 years of age. The likelihood of finding a colorectal cancer (CRC) at the first colonoscopy at this age is quite low (in the range of 1/1000 among asymptomatic, average-risk individuals); however, the finding of premalignant lesions (adenomatous polyps [APs] and serrated polyps [SPs]) is common, being found in 30–50%. It is speculated that the features of premalignant lesions at the index colonoscopy can be used to more precisely direct the timing of subsequent surveillance exams. Two recently published studies investigate how the presence and pathological features of premalignant lesions at the index colonoscopic exam can help predict the likelihood of future risk of neoplastic lesions.1,2
Polychronidis et al1 analyzed a prospectively studied cohort managed at the Harvard School of Public Health, which involved 156,699 colonoscopies from 2007 to 2017. After a median follow-up duration of 5.3 years, those with high-risk APs at the initial exam had hazard ratios (HRs) for CRC or recurrent high-risk APs of 5.44 (95% CI, 3.56–8.29) compared with those who had no polyps at the index study. Moreover, those with high-risk SPs had an HR of 8.35 (CI, 4.20–16.59). Surveillance colonoscopy reduced the risk of subsequent CRC to 0.61 (CI, 0.39–0.98) among those who had high-risk polyps removed and 0.57 (CI, −0.35–0.92) after removal of the low-risk polyps. Patients with high-risk lesions at both the index and surveillance colonoscopy were twice as likely to have had proximal colonic lesions, suggesting contributions of incomplete resection, missed lesions, and field effects as causes of interval neoplasia.
Baile-Maxia et al2 conducted a systematic review and meta-analysis of 14 clinical trials involving 493,949 patients to determine the incidence of CRC or advanced neoplasia (polyps >10 mm or those with dysplasia) at surveillance colonoscopy, at a mean follow-up duration of 4.9 years after the removal of an index SP, AP, or CRC. The findings can be best understood when the data are simplified to reflect the HR (and 95% CI) for CRC in order of risk after removal of the following lesions at the index colonoscopy.
The authors conclude that CRC risk is significantly higher after the removal of a baseline SP with dysplasia or advanced features, compared with non-advanced lesions or colonoscopies with normal findings. SPs with dysplasia are particularly important predictors of CRC risk, whereas size, number, and location were less so in this study.
These two studies underscore that the risk for colorectal neoplasia after an index screening colonoscopy is significantly related to finding an advanced polyp in the index exam compared with a colonoscopy with no findings. The presence of dysplasia in SPs is particularly important and seems to be the most critical of the “advanced” features for this lesion. These are large studies, which can be used to help develop more precise approaches to the development of follow-up surveillance colonoscopy strategies in patients who have benign polyps found at their initial screening colonoscopy.
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