PMO-206 Post colonoscopy cancers in 5-year interval
Authors: C Subbiah Somasundaram, D Ramanaden, I Finnie, A Baghomian
Journal: Gut (2012)

<h3>Introduction</h3> To evaluate the risk of colorectal cancer in a 5-year period after a negative colonoscopy (PCCRC). <h3>Methods</h3> Data of patients undergoing colonoscopy in a 1-year period from January to December 2004 collected from endoscopy database (847 cases), and matched electronically with patients diagnosed with CRC in the next 5 years. 60 matches were made. <b>Exclusion criteria:</b> Patients detected to have cancers by colonoscopy in 2004 (44 cases). <b>Inclusion criteria:</b> Patients with negative colonoscopy in 2004 with CRC from 2005 to 2009 were included (n=803). <h3>Results</h3> Four patients with negative colonoscopy in 2004 were diagnosed with CRC between 2005 to 2009. <b>Case 1</b>: M78 with diverticular disease in 2004 and iron deficiency anaemia 2005. OGD showed pyloric ulcer. Colonoscopy deferred as negative 1 year ago. In 2006 found to have <b>caecal cancer.</b> <b>Case 2:</b> M43 known IBD, on surveillance with negative colonoscopy in 2004 had <b>low rectal cancer</b> in 2005. <b>Case 3:</b> M66 had four adenomas (ascending colon, hepatic flexure, splenic flexure and 20 cm from anal verge) removed in July 2004. <b>Rectal Malignancy</b> detected in 2005. <b>Case 4:</b> F76 incomplete colonoscopy in 2004 due to a tight sigmoid diverticular stricture, developed <b>sigmoid cancer</b>in 2008. <b>4 PCCRCs (1 Caecal, 1 Sigmiod, 2 Rectal) detected out of 803 patients in an interval of 5</b> <b>years with a miss rate of 0.49% over 5</b> <b>years. Three were males. Age range 43–78</b> <b>years.</b> <h3>Conclusion</h3> <b>What is known:</b> Previous studies<sup>1</sup> have shown that female sex diverticular disease, older age,<sup>2 3</sup> right sided cancers<sup>1–5</sup> IBD, incomplete colonoscopy<sup>2 3</sup> are all risk factors for missed CRCs. <b>What this study found:</b> 3 out of 4 missed cancers were in males and 3 out of 4 were left sided cancers, two of them in rectum. Our miss rate was 4/803 that is 0.49% compared to an average of 5% in other studies<sup>1–6</sup> and similar to the miss rate in the National Polyp study. <b>What this study adds:</b> Diligent examination of the rectum is important; particularly in IBD patients on surveillance. It is important to retroflex in rectum to inspect the anal verge. Left sided cancers comprised the major part of missed cancers. <h3>Competing interests</h3> None declared. <h3>References</h3> 1. <b>Bressler B</b>, <i>et al.</i> Rates of new or missed colorectal cancers after colonoscopy and their risk factors. <i>Gastroenterology</i> 2000. 2. <b>Shah HA</b>, <i>et al.</i> Factors associated with incomplete colonoscopy. <i>Gastroenterology</i> 2007. 3. <b>Aslinia F</b>, <i>et al.</i> Quality assessment of colonoscopic cecal intubation: an analysis of 6 years of continuous practice at a university hospital. <i>Am J Gastroenterology</i> 2006. 4. <b>Lakoff J</b>, <i>et al.</i> Risk of developing proximal versus distal colorectal cancer after a negative colonoscopy. <i>Clin GastroenterolHepatol</i> 2008. 5. <b>Rex DK</b>, <i>et al.</i> Relative sensitivity of colonoscopy and barium enema for detection of colorectal cancer. <i>Gastroenterology</i> 1997. 6. <b>Winawer SJ</b>, <i>et al.</i> Prevention of colorectal cancer by colonoscopic polypectomy.The National Polyp Study. <i>N Engl J Med</i> 1993.