When Is A Colonoscopy Not a Colonoscopy Dr Linus Chang Gastroenterologist

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  • When Is A Colonoscopy Not a Colonoscopy Dr Linus Chang Gastroenterologist
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  • Mrs BP 67yo woman referred for screening colonoscopy for +ve FOB Index colonoscopy in Sep 2009 Multiple polyps; largest was resected (TVA) Rebooked 8mo later for resection of remaining smaller polyps
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  • Mrs BP Colonoscopy 6mo later Caecal ulcer Failed to lift with submucosal injection of saline Biopsied -> Carcinoma in situ
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  • Caecal view Sep 2009Caecal view May 2010
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  • Mrs BP - Surgery Proceeded to R hemicolectomy Early T2 CRC -> just infiltrating muscularis propria Loss of nuclear staining seen for MLH1 and PMS2 (consistent with microsatellite instability) 0/10 lymph nodes involved No adjuvant chemo recommended Tumour was surrounded by flat lesions which were sessile serrated adenomas (SSA)
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  • Colorectal Cancer 2 nd most common cause of cancer death Causes 9% of cancer death overall
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  • Colonoscopy in screening for CRC Screening colonoscopy in 1994 asymptomatic adults 5.7% had advanced neoplasms Lieberman DA, et al N Engl J Med. 2000;343(3):162 Asymptomatic individuals (mean age 61) colonoscoped then followed for 8 years have reduced CRC incidence and death compared to expected incidence and SEERS data Kahi CJ, et al. Clin Gas Hepat. 2009;7(7):770
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  • Expected Adenoma Detection Rate Overall, in 10034 colonoscopies, 29.1% had at least 1 adenoma removed. Males vs Females (24.5% vs 16.7%; p 1 adenoma or cancer 14.6% (13.2-16)23.3%(20.1-26.9)35.2%(29.5-41.4) > 1 nonadenoma/non cancer 26%(24-28.1)27.6%(24.3-31.3)29.3%(24.5-34.6)
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  • Risks of Colonoscopy 1 in 1000 of perforation or major bleeding 0.8/1000 if no biopsy 7/1000 if polypectomy or biopsy
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  • Polyp detection depends on endoscopist Risk of interval cancer between screening colonoscopy and repeat procedure depends on endoscopists adenoma detection rate Withdrawal time of 6 minutes or more increases adenoma detection rate Barclay RL, et al. N Engl J Med. 2006;355(24):2533
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  • Less effective in R sided lesions? Colonoscopy reduces deaths mainly from L sided CRC, but not R sided lesions: Baxter NN, Ann Intern Med. 2009;150(1):1. Singh H, Gastroenterology. 2010;139(4):1128 5% of CRCs arise as interval cancers following a colonoscopy
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  • Sessile Serrated Adenomas Distal polyps usually follow conventional adenoma-carcinoma sequence Up to 20% of all CRCs may arise from serrated polyps Only recognised as recently as 2003 Serrated pathway polyps become cancers with high levels of microsatellite instability (MSI) Can become cancers more rapidly than conventional adenomas
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  • This is what were missing!
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  • Sessile Serrated Adenomas (2) SSAs represent 1-9% of all polyps Present in 1-4% of the general population Median age of patients 61 Trend toward female gender bias More commonly in the proximal colon Endoscopic appearance: 5mm or larger Flat or depressed Covered by adherent layer of yellowish mucus In patients with at least one SSA 12% have LGD; 2% have HGD; 1% have adenocarcinoma Huang CS, et al. Am J Gastro 2011; 106: 229-240
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  • Natural History of SSAs Lu F, et al. Am J of Surg Path 2010; 34(7):927-934 All colonic polyps dx between 1980-2001 studied 1402 hyperplastic polyps 81 polyps in 55 pts rediagnosed as SSA 40 SSA pts with no prev hx of CRC or AP-HGD Of these, 5 developed CRC, 1 developed AP-HGD CRC more commong in SSA pts than in controls with HP (12.5% vs 1.8%) and AP (12.5% vs 1.8%) All subsequent CRC or AP-HGD developed in proximal colon 4 of 5 subsequent CRC showed MSI Conclusion: 15% of SSA pts developed subsequent CRC or AP-HGD; especially in the R colon
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  • Risk factors for developing SSAs Cigarette smoking Obesity Female gender Family history of CRC or polyps
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  • How quickly to SSAs progress to cancer We dont know Case study suggesting SSA-> CA in 8 months Mrs BP
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  • Surveillance post-resection SSA with no dysplasia 5 years if