SERRATED POLYPOSIS SYNDROME
A 72 year old male had a history of atrial fibrillation, hypertension, peripheral vascular disease and type 2 diabetes mellitus. He was taking Clopidogrel and Apixaban (a directly acting oral anti-coagulant). About 3 years ago, he had a laparoscopic anterior resection for cancer of the sigmoid colon (Dukes B, pT3,pN0,M0). A follow-up colonoscopy 2 years ago was normal to the caecum. Eighteen months ago, he underwent a left aorto-femoral bypass for critical ischaemia. Four months ago, he was referred by his GP for an urgent (2 week wait) colonoscopy and OGD because of iron deficiency anaemia. The procedures were performed by a locum gastroenterologist; the OGD was normal and colonoscopy showed a "10mm caecal polyp" which was left untouched as patient was taking Clopidogrel and Apixaban. He now attends for a further elective colonoscopy to remove the caecal polyp. However, at colonoscopy, I found more than I bargained for (see video)...
Eight serrated polyps were removed and a few smaller distal polyps were left behind for another day.
Serrated polyps can be multiple and if present in sufficient numbers and size can meet the criteria for Serrated Polyposis Syndrome (SPS), previously called HP syndrome.
The current WHO definition of SPS (2010)* is as follows:
1. At least five serrated polyps proximal to the sigmoid colon, two of which are greater than 10 mm in diameter.
2. Any number of serrated polyps occurring proximal to the sigmoid colon in an individual who has a first-degree relative with serrated polyposis.
3. More than 20 serrated polyps of any size distributed throughout the colon.
[*Serrated lesion refers to any combination of hyperplastic polyps and sessile serrated polyps.]
No genetic mutation is identified for the majority of cases of SPS. The risk of colorectal cancer (CRC) in first-degree relative of patients with SPS is five times that of the general population. There are no report showing an association with extracolonic carcinoma.
In FOBT-based screening, the prevalence of SPS may exceed 1:300, although the rate in colonoscopy-based programmes is about 1:2000. Recent studies from the Netherlands and the USA have shown an increased risk of CRC during colonoscopic surveillance of 7% at 5 years and two cancers in 44 patients over 2 years. A large international multicentre series reported a lower rate of 1.9 events/1000 person-years surveillance (95% CI 0.3 to 6.4). A multicentre Spanish series also reported a lower than previously reported risk, 1.9% CRC risk at 5 years.
The risk of CRC that can be reduced, at least over 5 years, by intensive colonoscopic surveillance. The BSG position statement (2017) recommends that patients who meet the WHO criteria for SPS should be offered one to two yearly colonoscopic surveillance.
REFERENCES
1. Snover D, Ahnen DJ, Burt RW, et al. Serrated polyps of the colon and rectum and serrated polyposis. WHO Classification of Tumours of the Digestive System. 4th ed. Lyon: IARC, 2010.
2. East JE, Atkin WS, Bateman AC, et al British Society of Gastroenterology position statement on serrated polyps in the colon and rectum, Gut 2017;66:1181-1196.
https://gut.bmj.com/content/66/7/1181
3. Obuch JO, Pigott CM, and Ahnen DJ, Curr Treat Options Gastroenterol. 2015 Mar; 13(1): 156–170, Sessile Serrated Polyps: Detection, Eradication, and Prevention of the Evil Twin
https://www.ncbi.nlm.nih.gov/pubmed/25623474
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