Serrated polyposis syndrome

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Background

The World Health Organization (WHO) defines serrated polyposis syndrome as the presence of any of the following:[1][2]

1. at least 5 serrated polyps proximal to the sigmoid colon, with ≥ 2 of these being > 10 mm
2. any number of serrated polyps proximal to the sigmoid colon in an individual who has a first-degree relative with serrated polyposis syndrome
3. > 20 serrated polyps of any size, but distributed throughout the colon.

The polyp count is usually interpreted as being cumulative. This definition is based on expert opinion and may be revised in future when the aetiology is better understood. Serrated polyposis syndrome was originally considered rare but with improved endoscopic detection of serrated polyps, it is becoming more common for an individual to meet this definition.[1] Often some conventional adenomas are also present. The prevalence of colorectal cancer at the time of diagnosis is high with estimates between 25% and 40%.[2] However, once a diagnosis is made and appropriate colonoscopic surveillance is being undertaken, the risk is lower with an estimate of 1.9% over 5 years.[3]

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Management

No systematic reviews on this topic were undertaken in the development of this section. The guidance on serrated polyposis syndrome is based on recent international guidelines.[1][2][4][3] See Guidelines Development for more information.

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Genetic testing

Although there is often a family history of colorectal cancer, it is uncommon for serrated polyposis syndrome to occur in more than one family member.[2] The genetic cause of serrated polyposis syndrome has not been established and genetic testing is not available.

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Surveillance and surgical management

Practice pointA recommendation on a subject that is outside the scope of the search strategy for the systematic review, based on expert opinion and formulated by a consensus process.Question mark transparent.png

The type of surgical procedure should be individualised according to the distribution of polyps and patient factors, but most patients will be adequately managed by either a segmental (partial) resection or extended resection (total colectomy with an ileorectal anastomosis). It is reasonable to offer colonoscopic surveillance every 5 years to first degree relatives of serrated polyposis syndrome patients, given their increased risk of colorectal cancer.[1] There is not clear evidence regarding the age to commence screening of first degree relatives but reasonable choices would be age 40 or 10 years younger than the youngest age of serrated polyposis syndrome diagnosis in the family, whichever comes first.

Next section: supplement state and territory-based familial cancer registries
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References

  1. 1.01.11.21.3 Syngal S, Brand RE, Church JM, Giardiello FM, Hampel HL, Burt RW, et al. ACG clinical guideline: Genetic testing and management of hereditary gastrointestinal cancer syndromes. Am J Gastroenterol 2015 Feb;110(2):223-62; quiz 263 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/25645574.
  2. 2.02.12.22.3 Cancer Institute NSW. eviQ Cancer Genetics Referral Guidelines for Colorectal Cancer or Polyposis Risk Assessment and Consideration of Genetic Testing. [homepage on the internet] Sydney; 2016 [cited 2016 Sep 6]. Available from: https://www.eviq.org.au/Category/tabid/65/categoryid/6/Default.aspx.
  3. 3.03.1 Carballal S, Rodríguez-Alcalde D, Moreira L, Hernández L, Rodríguez L, Rodríguez-Moranta F, et al. Colorectal cancer risk factors in patients with serrated polyposis syndrome: a large multicentre study. Gut 2015 Aug 11 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/26264224.
  4. Robays J, Poppe B. Oncogenetic testing for Lynch syndrome and familial adenomatous polyposis. Brussels: Belgian Health Care Knowledge Centre (KCE); 2014.
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