Roel Bogie

Chapter 7

Detection and resection of colorectal neoplasms Detection

The majority of post-polypectomy surveillance guidelines use risk stratification to determine surveillance intervals ( Figure 7.1 ). Patients with multiple, large, proximal adenomas, or adenomas with unfavorable histology (villosity or high-grade dysplasia) at baseline colonoscopy have a greater risk of synchronous and metachronous neoplasms, 44-46 justifying more intensive surveillance. Evidence on the optimal post-polypectomy surveillance intervals is scarce. 12, 47 Lack of conclusive data from randomized controlled trials and uncertainty surrounding many issues partly explain discrepancies in recommendations. For example, there is variation between society guidelines with regard to definition of risk factors and recommended surveillance intervals in some subgroups ( Figure 7.1 ). To ensure a high-quality surveillance program, the diagnostic and therapeutic yield at the index examination should be optimized. A recent large multicenter study from the UK (Quality Improvement in Colonoscopy study), found that implementation of a bundle of measures (e.g. withdrawal time ≥6 minutes; use of butyl scopolamine; position change during colonoscopy to optimize visualization; and rectal retroflexion) improves adenoma detection rates. 48 To improve uniformity in surveillance practice, the post-polypectomy surveillance guideline of the ESGE 1 recommend risk stratification in two groups: (1) low risk group, which consists of patients with 1 or 2 non-advanced adenomas versus (2) high-risk group, which consists of patients with ≥3 adenomas or ≥1 advanced adenoma (≥10mm, villous histology or high-grade dysplasia). The ESGE guideline recommend that the low-risk group further participates in the screening program or return for follow-up colonoscopy after 10 years (whatever option is available). Conversely, patients in the high-risk group are recommended to undergo colonoscopy surveillance 3 years after the baseline colonoscopy ( Figure 7.2 ). 1 Both recommendations are strong and based on moderate quality evidence: a meta-analysis found that advanced neoplasia was diagnosed during follow-up in 1.6% of patients without neoplasia and in 3.6% of those with low-risk findings (relative risk of 1.8, 95% CI: 1.3 – 2.6). 49 A prospective Korean study showed that advanced adenoma recurrence at 5 years after a baseline colonoscopy was similar in low-risk patients versus patients without neoplasms, concluding that extending the surveillance interval beyond 5 years for the low-risk patients is safe. 50 Case-control studies confirm the absolute low risk of CRC in the 5 years after polypectomy. 51-53 In a pooled analysis of eight American, prospective studies including 9167 patients, 15.5% of the high risk group and 6.9% of the low-risk group developed advanced adenoma during follow-up, whereas 0.8%of thehigh-risk and0.5%of the low-riskpatients developedCRC. 8 Twometa-analyses confirmed that patients with more than two adenomas had a higher risk of developing advanced adenomas in surveillance than patients with one or two adenomas at baseline. 15, 54 Of note, most studies did not specifically examine the quality of index-colonoscopy and relation with metachronous neoplasms. Data from the ongoing randomized controlled Japan Polyp Study indicate that two complete colonoscopies (at baseline and after 1 year) have the potential to lengthen subsequent follow-up intervals. 17 Several distinct features of current post-polypectomy surveillance guidelines need to be acknowledged. The post-polypectomy surveillance guideline of the British Society of Gastroenterology and the Association of Coloproctology for Great Britain and Ireland (UK guideline) classify three risk subgroups: low, intermediate and high-risk groups recommending surveillance intervals of 5, 3 and 1 year(s), respectively. 3 Martinez et al. compared the outcomes of applying

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