Is surveillance recommended?

These three polyps were removed en-bloc from the proximal colon. In an earlier examination 2 SSL's had been removed. A subsequent colonoscopy finds no further polyps. 
WHAT WOULD YOU ADVISE AS REGARDS SURVEILLANCE?

■ There is no need for surveillance

You may be right if the patient is old and with multiple comorbidities!

■ Surveillance every 2 years

Yes, this is what guidelines usually recommend for 'SPS'

■ Surveillance every 5 years

Too long if pt fulfills WHO criteria for SPS

explanation

If course, this patient has 'Serrated Polyposis Syndrome'. It's important to recognise that the serrated polyp count is cumulative over multiple colonoscopies.

The recently updated 2019 WHO criteria for Serrated Polyposis Syndrome recognize two types of the syndrome: a 'proximal phenotype' with serrated polyps proximal to the rectum, all being ≥5 mm in size, with at least two being ≥10 mm in size (criterion I 2019), and a more 'distal phenotype' with more than 20 serrated polyps of any size throughout the large bowel (criterion II 2019) [Gastroenterology 2020;158:1520–23]. 

Personally, I believe that there are more than two subtypes of the Serrated Polyposis Syndrome.  There is accumulating evidence that the syndrome includes multiple conditions with variable phenotypes and with different risks of progression to CRC [Gut 2010;59:1094–1100].  This would explain the huge range of cancer risk (25%-70%) in published studies [GIE 2016;83:563–65]. 

Of course, the likely mixture of several 'syndromes', makes writing guidelines difficult. A recent consensus update by the US Multi-Society Task Force recommend offering a follow-up colonoscopy to average risk patients based on number and size of the SSL's found [GIE 2020;91:463–85].  Interestingly, the US guidelines make a distinction between 'hyperplastic polyps' and 'sessile serrated polyps' although pathologists can't reliably make that distinction.  Furthermore, the guidelines excludes patients with an increased life-time risk of cancer which of course excludes patients with Serrated Polyposis Syndrome. 

I find it all somewhat confusing!  James East's BSG guideline 2017  [ Gut 2017;0:1–16 ] recommend surveillance every other year whilst the more recent  BSG/ACPGBI guideline of 2020 [ Gut 2020;69:201– 23 ] would seem to suggest 3 yr for all 'high risk cases. But these guidelines expressively don't cover pts with hereditary cancers.   Hereditary cancers are instead covered by the BSG/ACPGBI 2019 guideline [ Gut 2019;0:1–34 ] which recommends annual surveillance until all polyps are cleared and then every 2 years. 

Finally, I admit that I also take the age of the patient into consideration as well as the presence of both serrated and adenomatous polyps. A 40 year old person is surely more likely to benefit from surveillance than a 75 year old person with multiple comorbidities?   In particular, I would worry about a young patient, perhaps 35 year old, with 1-2 large serrated polyps and perhaps only a single adenoma.  Current guidelines don't flag these individuals up but personally, I would organise another surveillance colonoscopy in a few years time.

Clearly, more research is needed to unpick the different serrated sub-pathways !