1. Am J Gastroenterol 2012; 107:1213–1219 12 June 2012 R3. 김동희 /prof. 이창균

2. Colonoscopy, sigmoidscopy is associated with a decreased risk of colorectal cancer. more effective in reducing the risk of distal than proximal malignancies.  Biological differences between proximal and distal colon polyps  differences in the quality of the colon preparation between the proximal and distal colon  insufficient endoscopist training

3. Sessile serrated polyps proposed to have a particularly important role in proximal colon cancer development. To gain insight into the differences between proximal and distal colon endoscopic performance Association between previous endoscopy and the risk of different types of colorectal cancer precursor lesions ?

4. Study population  Inclusion criteria  Washington state  any indication between 1998 – 2007(index colonoscopy)  aged 50 – 79 years  adenomas, hyperplastic polyps, normal findings  Exclusion criteria  current or previous colorectal cancer  inflammatory bowel disease  familial adenomatous polyposis,  Lynch Syndrome  previous colectomy  colonoscopy within the 12 months before the index colonoscopy  incomplete index colonoscopies

5. Data collection  previous endoscopy, demographic characteristics  family history of colorectal cancer, height, weight  physical activity, alcohol consumption, smoking, aspirin use,  reproductive history, hormone use. (For women )  74 % (N=2,485) consented to answer the questionnaire  399 were excluded  missing data on previous endoscopy procedures or missing pathology data on polyp size

6. Case – control classification  pathology reviews  the size and anatomic site of each polyp  Definition  Advanced adenoma  ≥ 10 mm, ≥ 20 % villous components, high-grade dysplasia  Sessile serrated polyps  crypt serration, crypt dilatation, crypt branching, horizontal crypt extensions, distortion of architectural organization and maturation  Control  Hyperplastic polyps of any size  tubular adenomas < 10 mm  no advanced adenomas or SSP  213 adenoma cases, 172 SSP cases, 1,704 controls

10. endoscopy >10years ago, never had endoscopy  advanced adenomas, OR = 0.41, 95% CI: 0.27– 0.62 advanced adenomas, endoscopy >5 years ago  OR = 0.36, 95% CI: 0.25– 0.53 advanced adenomas, endoscopy 2– 5 years ago  OR = 0.38, 95% CI: 0.26– 0.56 SSPs and endoscopy >5 years ago  OR = 0.73, 95% CI: 0.48– 1.09 SSPs and endoscopy 2– 5 years ago,  OR = 0.86, 95% CI: 0.58– 1.29

11. A strong, statistically significant inverse association between advanced adenomas and previous endoscopy The effect of endoscopy differs between advanced adenomas and SSPs. Awareness of the importance of SSPs may have implications for proximal colon cancer prevention