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colorectal adenomatous polyp; tubular adenoma; villous adenoma

Etiology: - risk factors - antibiotic use in young adulthood & middle age - dose-dependent relationship Pathology: Most colorectal carcinomas begin as adenomatous polyps. Only a minority of adenomatous polyps develop into cancer (< 1%). Gross morphology: 1) pedunculated 2) sessile (flat)* * Cancers develop more frequently from sessile polyps. Histology: 1) tubular 2) villous or papillary* 3) tubulovillous * villous adenomatous polyps are more frequently sessile polyps & develop into adenocarcinoma 3 times more frequently than tubular adenomatous polyps * images (review) [9] Genetics: - siblings of patients with advanced adenomatous polyps are at increased risk for advanced colorectal adenomas [8] Clinical manifestations: - most colonic adenomatous polyps produce no symptoms Prognosis: - < 1.5 cm: low probability of transformation - 1.5-2.5 cm: 2-10% probability of transformation* - > 2.5 cm: > 10% probability of transformation* * colorectal cancer risk increased only for adenomas >= 20 mm or with high-grade dysplasia [13] relative risk for advanced adenoma 36 months later [11] - 1-2 adenomas, of which at least 1 was small (5-9 mm) = 1.5 - 3-10 small adenomas (5-9 mm) = 1.7 - 3-10 adenomas, of which at least 1 was small (5-9 mm) = 2.0 - advanced adenoma = 2.5 colorectal cancer risk & (mortality) for index colonoscopy [14] - no adenoma = 3.4 (0.7) - 1-2 small adenomas < 10 mm = 4.5 (0.8) - > 3 adenomas or adenoma > 10 mm or villous features or high-grade dysplasia = 13.8 (2.1) Management: 1) entire bowel should be visualized by colonoscopy since multiple lesions are present in 1/3 of cases 2) repeat colonoscopy a) 1-2 small tubular adenomas, follow-up colonoscopy in 5-10 years [6] - 5 years is reasonable [12] b) 3-10 adenomas, any adenoma with villous elements or high-grade dysplasia, or an adenoma measuring >= 1 cm should have another exam in 3 years [3] c) > 10 adenomas, & those with large sessile adenomas removed piecemeal, should have a follow-up in < 3 years d) sessile adenomas removed in piecemeal fashion should have follow-up in 2-6 months e) large adenomas (> 2 cm) or well differentiated colorectal adenocarcinomas with clean margins should have follow-up exam in 3-6 months [5] f) information from previous exams may be useful [4] 3) prevention - calcium & vitamin D of no benefit [7]

Related

adenocarcinoma of the colon &/or rectum

Specific

diminutive colorectal adenoma

General

adenoma colorectal polyp precancerous condition

References

  1. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 1426
  2. Internal Medicine News, Dec 1, 2005 quotes Bakhru M, at the annual meeting of the American College of Gastroenterology
  3. Laiyemo AO, Murphy G, Albert PS, Sansbury LB, Wang Z et al Postpolypectomy colonoscopy surveillance guidelines: predictive accuracy for advanced adenoma at 4 years. Ann Intern Med. 2008 Mar 18;148(6):419-26. PMID: 18347350 - Imperiale TF, Sox HC. Guidelines for surveillance intervals after polypectomy: coping with the evidence. Ann Intern Med. 2008 Mar 18;148(6):477-9. No abstract available. PMID: 18347353
  4. Robertson DJ et al. Using the results of a baseline and a surveillance colonoscopy to predict recurrent adenomas with high-risk characteristics. Ann Intern Med 2009 Jul 21; 151:103. PMID: 19620162
  5. Medical Knowledge Self Assessment Program (MKSAP) 15, 16, 17. American College of Physicians, Philadelphia 2009, 2012, 2015
  6. Chung SJ et al. Five-year risk for advanced colorectal neoplasia after initial colonoscopy according to the baseline risk stratification: A prospective study in 2452 asymptomatic Koreans. Gut 2011 Nov; 60:1537. PMID: 21427200 - Winawer SJ et al Guidelines for Colonoscopy Surveillance After Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer and the American Cancer Society Gastroenterology, 2006, 130(6):1872-1885 PMID: 16697750 http://www.gastrojournal.org/article/S0016-5085(06)00561-0/abstract
  7. Baron JA, Barry EL, Mott LA et al A Trial of Calcium and Vitamin D for the Prevention of Colorectal Adenomas. N Engl J Med 2015; 373:1519-1530. October 15, 2015 PMID: 26465985 http://www.nejm.org/doi/full/10.1056/NEJMoa1500409
  8. Ng SC et al. Risk of advanced adenomas in siblings of individuals with advanced adenomas: A cross-sectional study. Gastroenterology 2015 Nov 13 PMID: 26584600
  9. Strum WB Colorectal Adenomas (images) N Engl J Med 2016; 374:1065-1075. March 17, 2016 PMID: 26981936 http://www.nejm.org/doi/full/10.1056/NEJMra1513581
  10. Cao Y, Wu K, Mehta R et al Long-term use of antibiotics and risk of colorectal adenoma Gut. April 2017 PMID: 28377387 http://gut.bmj.com/content/early/2017/03/16/gutjnl-2016-313413
  11. Anderson JC, Rex DK, Robinson C, Butterly LF. Association of small versus diminutive adenomas and the risk for metachronous advanced adenomas: Data from the New Hampshire Colonoscopy Registry. Gastrointest Endosc 2019 May 21; PMID: 31125546 https://www.giejournal.org/article/S0016-5107(19)31721-3/pdf - Sekiguchi M, Otake Y, Kakugawa Y, Matsumoto M et al. Incidence of advanced colorectal neoplasia in individuals with untreated diminutive colorectal adenomas diagnosed by magnifying image-enhanced endoscopy. Am J Gastroenterol 2019 Jun; 114:964 PMID: 31082873
  12. Meester RGS, Lansdorp-Vogelaar I, Winawer SJ et al High-Intensity Versus Low-Intensity Surveillance for Patients With Colorectal Adenomas: A Cost-Effectiveness Analysis. Ann Intern Med. 2019. Sept 24 PMID: 31546257 https://annals.org/aim/article-abstract/2751914/high-intensity-versus-low-intensity-surveillance-patients-colorectal-adenomas-cost - Weinberg DS, Schoen RE Preneoplastic Colorectal Polyps: "I Found Them and Removed Them - Now What?" Ann Intern Med. 2019. Sept 24 PMID: 31546250 https://annals.org/aim/article-abstract/2751915/preneoplastic-colorectal-polyps-i-found-them-removed-them-now-what
  13. Wieszczy P, P, Kaminski MF, Franczyk R et al. Colorectal cancer incidence and mortality after removal of adenomas during screening colonoscopies. Gastroenterology. 2019 Sep 26. pii: S0016-5085(19)41344-9. PMID: 31563625 Free Article
  14. Duvvuri A, Chandrasekar VT, Srinivasan S et al. Risk of colorectal cancer and cancer related mortality after detection of low-risk or high-risk adenomas, compared with no adenoma, at index colonoscopy: A systematic review and meta-analysis. Gastroenterology 2021 Jan 29; [e-pub] PMID: 33524401 https://www.gastrojournal.org/article/S0016-5085(21)00320-6/pdf
  15. Lieberman DA, Rex DK, Winawer SJ et al. Guidelines for Colonoscopy Surveillance After Screening and Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology. 2012 143(3):844-857 PMID: 22763141 https://www.gastrojournal.org/article/S0016-5085(12)00812-8/fulltext