First surveillance intervals following removal of serrated polyps (with or without conventional adenoma)

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Definition

Serrated polyps (SPs) include the premalignant lesions sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs) and the usually benign hyperplastic polyps. SSAs, TSAs and large (≥10mm) hyperplastic polyps are clinically significant serrated polyps.

This section considers first surveillance intervals following removal of clinically significant SPs only and with synchronous conventional adenomas.

For surveillance intervals following removal of conventional adenomas only see First surveillance intervals following removal of low-risk conventional adenomas only (SAD1) and First surveillance intervals following removal of high-risk conventional adenomas only (SAD2).

For information and guidance on serrated polyposis syndrome, see Serrated polyposis syndrome.

Background

At the time of the previous edition of these guidelines (Australian clinical practice guidelines for surveillance colonoscopy),[1] there was insufficient evidence to differentiate follow-up protocols for SPs from those for standard adenoma follow-up. Since then, the 2010 World Health Organization classification has become well established, with reduced variability among histopathologists in applying these diagnostic criteria.[2] In addition, there has been improved endoscopist recognition of proximal serrated polyps although there is still great variability.[3] Although the evidence base remains limited, there is now sufficient information to allow specific recommendations.

Sessile serrated adenomas

Sessile serrated adenomas (SSAs) are expected to be diagnosed in over 5% of colonoscopies and undoubtedly have malignant potential.[3]

Predominantly found in the proximal colon, SSAs are subtle, sessile lesions and this may make it difficult to define the edges of the lesion to ensure complete resection.

The natural history of SSAs is still imperfectly understood but recent evidence suggests SSAs without dysplasia are indolent lesions with a mean dwell time of over 15 years.[4] If cytological dysplasia does develop, the dwell time is thought to be short and carcinoma may develop in less than one year.[4][5][6][7]

Traditional serrated adenomas

Traditional serrated adenomas (TSAs) are rare, accounting for only approximately 1% of all polyps. They are typically polypoid lesions in the distal colon and their molecular features suggest they should be treated like advanced conventional adenomas, with a significant risk of progression to malignancy if not resected.[4]

Due to their rarity, there are no meaningful data regarding the risk of metachronous neoplasia (MNMetachronous neoplasia) after their removal and international guidelines are based solely on expert opinion.

Hyperplastic polyps

Hyperplastic polyps (HP) are common. Small, distal HPs have no significant malignant potential.

Proximal HPs are early stage lesions unlikely to progress unless they develop features of an SSA. However, a true proximal HP is unlikely to be over 1cm in size; such lesions should be reviewed by an expert histopathologist to confirm the histopathological diagnosis.[4]

Advanced serrated polyps

Advanced serrated polyps (ASPAdvanced serrated polyp) refer to a sessile serrated adenoma ≥10mm in size and/or with associated conventional dysplasia, or traditional serrated adenomas of any size.

Serrated polyposis syndrome

Serrated polyposis syndrome is described in detail in Clinical practice guidelines for the prevention, early detection and management of colorectal cancer[8] (see Serrated polyposis syndrome). No genetic cause has been established and it is possible there is a continuum between patients with multiple sporadic SSAs and those meeting the definition of serrated polyposis. This is particularly the case for patients meeting the World Health Organization definition of at least 5 serrated polyps proximal to the sigmoid colon with ≥2 of these being >10mm and the count being cumulative.

When serrated polyposis syndrome is first diagnosed, several colonoscopies may be required within 1–2 years to clear the colon of significant polyps. If this can be achieved, there is expert consensus that the risk of cancer justifies ongoing surveillance colonoscopy every 1 to 3 years with the aim of removing all polyps ≥5mm and that, if this is impossible, colectomy and ileorectal anastomosis should be considered. This is supported by direct evidence.[9][10][11]Back to top

Evidence

What is the appropriate first surveillance interval following complete removal of serrated polyps? [SAD4]

Systematic review evidence

The systematic review identified one level II study from Argentina with a high risk of bias[12] and two level III-2 studies from the USAUnited States of America with a low risk of bias.[13][14] Overall, the evidence is not necessarily generalisable to the Australian healthcare environment, but can probably be sensibly applied. Importantly, the colonoscopies in these studies were performed between 2004 and 2011 and histopathology was meticulously assessed. Although colonoscopy quality parameters were included, the SSA detection rates were still lower than the 5% anticipated with high quality colonoscopy (suggesting a level of missed lesions).[3] The outcomes assessed were various combinations of the incidence of metachronous colorectal cancer (CRCColorectal cancer), advanced conventional adenomas, SSAs and ASPs.

The quality of the three studies was low. Limited power precluded definitive conclusions.

The systematic review findings are summarised in Table 10 below.

Risk of metachronous colorectal cancer

Three of four cohort studies reported no incidences of colorectal cancer within 3–5 years for those classified at index as having clinically significant serrated polyps, SSAs or serrated adenomas with or without non-advanced or advanced adenoma. For those with SSAs coexisting with high risk adenoma at index, a 1.00% incidence of colorectal cancer (one case) at a mean and standard deviation of 3.54 (±1.43) years was reported.

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Risk of metachronous advanced conventional adenoma

The US study by Macaron et al[14] found that having an SSA as well as either low-risk or high-risk conventional adenoma did not significantly change the risk of metachronous advanced adenoma (MAAMetachronous advanced adenoma) during surveillance compared with not having an SSA. In their study, the risk was 27% at 3 years in the group with both high-risk adenoma with SSA, and 0% in the group with both low-risk adenoma and SSA.

In the Argentinian study by Pereyra et al,[12] there was no increased risk of MAAMetachronous advanced adenoma for synchronous low-risk adenoma and SSA, compared to low-risk adenoma alone.

In contrast, there was an increased risk of MAAMetachronous advanced adenoma in individuals with both high-risk adenoma and SSA, compared to high-risk adenoma alone (35.7% risk of MAAMetachronous advanced adenoma at 3 years for high-risk adenoma with synchronous SSA at baseline colonoscopy and 17.9% risk of MAAMetachronous advanced adenoma at 3 years for high-risk adenoma alone).

The US study of Melson et al[13] had a composite end-point including both MAAMetachronous advanced adenoma and metachronous advanced serrated polyps, so the incidence of MAAMetachronous advanced adenoma alone could not be determined with respect to the initial baseline findings. The findings suggest that the presence of an initial SSA increased the rate of metachronous advanced neoplasia, compared with conventional adenomas alone.

In subgroups of individuals with SSAs only at baseline colonoscopy, the 5-year risk of MAAMetachronous advanced adenoma was 12.8%in one study[14] and 8.3% in another,[12] but could not be determined in the third study. This is similar to the risk with low-risk adenoma at baseline.

Risk of metachronous ‘advanced neoplasia’

The study of Melson et al[13] used the end point of metachronous ‘advanced neoplasia’ during surveillance and defined this as MAAMetachronous advanced adenoma and/or SSA >1cm or SSA with high-grade dysplasia (HGDHigh grade dysplasia). Over a mean follow-up of 3.86 years, individuals with SSAs alone had an incidence of 6.31% of metachronous ‘advanced neoplasia’. Over a mean follow-up of 3.63 years, patients with 1 or 2 adenomas (including SSAs, if present) with each polyp <1cm had an incidence of 6.67% of advanced neoplasia. Over a mean follow-up of 1.98 years individuals with ≥3 adenomas (including SSAs if present) or an adenoma ≥1cm or with HGDHigh grade dysplasia or villous histology had an incidence of metachronous ‘advanced neoplasia’ of 18.75%. In all groups combined, the presence of an initial SSA increased the rate of metachronous ‘advanced neoplasia’ from 11.1% to 26.3%.

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Risk of metachronous serrated polyps

In the two US studies,[13][14] subjects without SSA at baseline had a very low incidence of any SSA during surveillance (<6%). Data addressing this could not be extracted from the Argentinian paper. In the study of Melson et al[13] the incidence of metachronous SSA was 33.3% over 3.94 years for individuals with SSAs with or without low-risk adenoma at baseline and was 32.98% over 3.54 years for individuals with high risk SSAs alone (≥1cm or dysplastic or ≥3) or SSA combined with high-risk adenoma. The incidence of metachronous SSA in individuals with SSA at baseline was 42.67% at 4 years in the Argentinian study.[12] It should be noted that the prevalence of SSA at baseline colonoscopy in these studies was <5% and some of these ‘metachronous’ SSAs were probably missed lesions. It will be interesting to determine the incidence of metachronous SSA when studies are published with a high prevalence of SSA at baseline colonoscopy.

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Risk of metachronous advanced serrated polyps

It is of major interest to determine if ASPs at baseline predict a higher risk of metachronous ASPs. These were not reported by the Argentinian study.[12] Melson et al[13] defined ASPAdvanced serrated polyp as: SSA ≥1cm or with HGDHigh grade dysplasia, but included these with MAAMetachronous advanced adenoma as a composite end point of metachronous ‘advanced neoplasia’, making it difficult to calculate the separate risks. Macaron et al[14] defined ASPAdvanced serrated polyp as: SSA or HP >1cm, SSA with conventional dysplasia or TSATraditional serrated adenoma of any size (Table 8). When comparing patients with SSA <10mm in size to those with ASPs at baseline colonoscopy, the incidences of metachronous ASPAdvanced serrated polyp at 3 years were 0% and 6.5%, respectively, and at 5 years were 4.3% and 11.5%. These findings demonstrate a nonsignificant trend (p=0.11) towards an increased incidence of metachronous ASPAdvanced serrated polyp over time in those with ASPAdvanced serrated polyp at baseline.[14] The study may have been underpowered to detect a difference in metachronous ASPAdvanced serrated polyp rates, as only 12 of the 157 patients had ASPs.

The Argentinian study[12] found no statistically significant increase in risk of metachronous SSA according to characteristics at baseline of: size >10mm (relative risk [RRRelative risk] 1.82, confidence interval [CI] 0.40–9.34, p=0.59), cytologic dysplasia (RRRelative risk 1.00, CI 0.15–4.32, p=1.00), right sided location (RRRelative risk 2.12, CI 0.47–11.53, p=0.48) and more than three SPs (RRRelative risk 1.69, CI 0.06–20.00. p=0.65). Again, power was limited by small numbers.

Cumulative incidence of metachronous advanced serrated polyp
Table 8. Cumulative incidence of metachronous advanced serrated polyp (Macaron et al [14])
Baseline findings SSA or TSATraditional serrated adenoma only SSA or TSATraditional serrated adenoma and LRALow risk adenoma SSA or TSATraditional serrated adenoma and HRAHigh risk adenoma
3 years 2% 4.85% 9%
5 years 7% 11% 9%
HRAHigh risk adenoma: high-risk adenoma; LRALow risk adenoma: low-risk adenoma; SSA: sessile serrated adenoma; TSATraditional serrated adenoma: traditional serrated adenoma
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Overview of additional evidence (non-systematic literature review)

Other longitudinal data

US Data from the New Hampshire ColonoscopyAn examination of the large bowel using a camera on a flexible tube, which is passed through the anus. Registry published after the completion of the systematic review period[15] provides further evidence that the combination of SSA and/or TSATraditional serrated adenoma with high-risk adenoma at baseline colonoscopy predicts a higher risk of metachronous high-risk adenoma . Over a median follow-up of 4.9 years, individuals with high-risk adenoma combined with either SSA or TSATraditional serrated adenoma at baseline had a 16.04-fold increased risk of metachronous high-risk adenoma compared with individuals with no polyps at baseline. Those with high-risk adenoma but no SSA or TSATraditional serrated adenoma had a 3.86-fold increased risk. The risk for the combination of low-risk adenoma and SSA or TSATraditional serrated adenoma at baseline was 2.88 (1.67–7.13) compared with those with no polyps, similar to that of those with low-risk adenoma alone, 1.93 (1.41–2.62).

This study also provided further evidence that having an SSA or TSATraditional serrated adenoma at baseline was associated with a significant risk of metachronous serrated polyps ≥1cm (9.6% over 4.9 years). The risk was present in those with serrated polyps alone or combined with either low-risk adenoma or high-risk adenoma . Of note, the SSA detection rate at baseline was <4% and some of the metachronous serrated polyps may have been missed lesions. The risk of metachronous serrated polyps ≥1cm was highest in those who had high-risk adenoma and serrated polyps ≥1cm at baseline, compared with individuals with no polyps (RRRelative risk 17.45). In contrast, individuals without an SSA or TSATraditional serrated adenoma at baseline had a very low risk of metachronous serrated polyps ≥1cm.

There is evidence that serrated polyps ≥10mm are more frequently associated with synchronous advanced neoplasia.[16][17] This evidence supports recommendations for earlier repeat surveillance in these patients in several clinical practice guidelines.[18][19][3][20]

There is strong evidence that SSAs with dysplasia have a high chance of becoming malignant and there have been numerous reports of SSAs ‘caught in the act’ of transitioning to conventional dysplasia and then to invasive carcinoma.[4][5][6][7] The relative rarity of these lesions compared with the proportion of cancers bearing the molecular hallmarks of the serrated pathway and the similarity of the mean ages of patients with SSA with dysplasia and with serrated pathway cancers suggests that SSAs with dysplasia have a short dwell time before malignant conversion.[4] Based on this evidence, several guidelines recommend earlier repeat surveillance in these patients.[18][19][3][20]Back to top

Clinical practice guidelines from other countries

Guideline recommendations are summarised in Table 11 below.

In 2012, the update of the guidelines for surveillance after polypectomy by the US Multi-Society Task Force (USMTFUS Multi-Society Task Force) on ColorectalReferring to the large bowel, comprising the colon and rectum. Cancer was published.[19] The recommendations on serrated polyps were based on low quality evidence available up to 2011. These guidelines recommended surveillance colonoscopy in 5 years for SSAs <10mm without dysplasia and in 3 years for SSAs ≥10mm or with dysplasia. In the same year an expert panel published a consensus opinion with similar recommendations, but with additional advice that if there were 3 or more SSAs <10mm without dysplasia the interval should be 3 years, and with dysplasia the interval should be 1 to 3 years.[20]

The European Society of Gastrointestinal Endoscopy (ESGEEuropean Society for Gastroenterology) guidelines published in 2013 again noted the low quality of evidence and recommended patients with SSAs ≥10mm or with dysplasia should be considered similar to those with high-risk conventional adenomas, and should be offered surveillance colonoscopy at 3 years.[18] The ESGEEuropean Society for Gastroenterology guidelines regarded other SSAs as similar to in risk to low-risk conventional adenomas, recommended surveillance colonoscopy at 10 years in these patients.

Most recently, the British Society of Gastroenterology (BSGBritish Society of Gastroenterology)[3] published a position statement on serrated polyps, in which they recommended that patients with SSAs ≥10mm or with conventional dysplasia should be offered surveillance colonoscopy at 3 years, but that other patients with SSAs should not be offered surveillance unless they meet criteria for serrated polyposis.

None of the above guidelines makes recommendations for combined serrated polyps and conventional adenomas, with the BSGBritish Society of Gastroenterology stating the groups should be considered separately. The BSGBritish Society of Gastroenterology [3] and USMTFUS Multi-Society Task Force[20] guidelines recommended surveillance at 3 years for all TSAs. All other guidelines recommended surveillance at 3 years for TSATraditional serrated adenoma ≥10mm, with other intervals varying from 'return to routine population screening' or colonoscopy at 5 or 10 years.

The question of the potential of large HPs is acknowledged by the BSGBritish Society of Gastroenterology, US Consensus Panel and ESGEEuropean Society for Gastroenterology in that they are included in the guidelines, with a 3-year surveillance interval recommended in two of the three guidelines and 5-year intervals in one for HPs ≥10mm. The US Consensus Panel goes further, recommending that patients with proximal small HPs (defined as proximal to the sigmoid and <10mm) should undergo surveillance depending on size and number.

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Evidence summary and recommendations

Evidence summary Level References
Three of four cohort studies reported no incidences of colorectal cancer within 3–5 years for those classified at index as having clinically significant serrated adenomas, sessile serrated adenomas or serrated adenomas with or without non-advanced or advanced adenoma.

For those with sessile serrated adenomas coexisting with high-risk adenoma at index, a 1.00% incidence of colorectal cancer (one case) at a mean and standard deviation of 3.54 (±1.43) years was reported.

II, III-2 [21], [14], [13], [12]
For those with sessile serrated adenomas at index, incidence of conventional adenoma was 34.67% after surveillance at 4.0±1.17 years. II [12]
In subgroup analysis according to adenoma risk at index colonoscopy, incidences of conventional adenoma were:
  • 59.09% after follow-up of 3.94±1.39 years among those with sessile serrated adenoma and low-risk adenomas
  • 68.09% after follow-up of 3.54±1.43 years among those with sessile serrated adenoma and high-risk adenomas.
III-2 [13]
Index features significantly associated with an increase in risk for metachronous conventional adenoma at an overall follow-up of 4.0±1.17 years were:
  • sessile serrated adenoma with cytological dysplasia (RRRelative risk 9.03; 95% CI=1.03–16.03, p=0.04)
  • sessile serrated adenoma with synchronous conventional adenoma (RRRelative risk 7.03; 95% CI 1.68–31.51, p=0.004).
II [12]
The cumulative incidence of advanced adenoma at 1–5 years increased at a similar rate for patients with index serrated adenoma only (0.0–10.0%) and those with both serrated adenoma and non-advanced adenoma (0.0–7.0%).

For those with serrated adenoma with advanced adenoma, cumulative incidence increased from 8.3–27.0% at 1–2 years and remained steady at 27.0% at 2–5 years.

III-2 [14]
There were no statistically significant differences in cumulative incidence of advanced serrated adenoma over 1–5 years between patients with index features of sessile serrated adenomas <10mm, and those with hyperplastic polyp or sessile serrated adenoma ≥10mm, traditional serrated adenoma or sessile serrated adenoma with low grade dysplasia (p=0.59). III-2 [14]
One study reported that, after 6 years follow-up, patients with an index sessile serrated adenoma only had a cumulative advanced neoplasm-free rate of 91.7% over the same period (6 years).

For those with an index sessile adenoma and synchronous low-risk adenomas, the cumulative advanced neoplasm-free rate was 100%.

For those with index sessile serrated adenomas and synchronous high-risk adenomas, the cumulative advanced neoplasm-free rate was 0%.

II [12]
For those with sessile serrated adenomas at index, the incidence of sessile serrated adenoma was 42.67% after follow-up 4.0±1.17 years. II [12]
In subgroup analysis according to adenoma risk status at index colonoscopy, incidences of sessile serrated adenoma were:
  • 33.33% among those with sessile serrated adenoma and low-risk adenoma, at follow-up of 3.94 ±1.39 years
  • 32.98% among those with sessile serrated adenoma and high-risk adenomas, at follow-up of 3.54 ±1.43 years.
III-2 [13]
In the one study that reported metachronous sessile serrated adenoma as an outcome, there was no significant evidence to suggest an increase in risk at an overall mean follow-up time of 4 (±1.17) years based on the following index features:
  • flat morphology
  • right side location
  • >10mm
  • >3 in number
  • cytological dysplasia
  • synchronous conventional adenoma
  • synchronous advance adenoma.
III-2 [13]
The incidence of advanced serrated polyps for those with index serrated adenoma only was 5.41% at a mean follow-up time of 3.86 (±1.39) years. III-2 [14]
Among patients with serrated adenomas at index and advanced serrated polyps at follow-up:
  • the incidence of advanced serrated polyps differed minimally according to adenoma status: 10.00% at follow-up of 3.63±1.47 years among those with both serrated adenoma and non-advanced adenoma at index, and 12.50% at follow-up of 1.98±1.41 years among those with both serrated adenoma and advanced adenoma at index.
  • all patients across all groups at follow-up had sessile serrated adenomas ≥10mm
  • proximal sessile serrated adenomas were detected at follow-up in two-thirds of patients with serrated adenomas only at index or both serrated adenoma and non-advanced adenomas at index, and in half of patients with both serrated adenoma and advanced adenomas at index
  • at follow-up, hyperplastic polyps ≥10mm occurred in one-third of patients with both serrated adenoma and non-advanced adenoma at index, and in half of those with serrated adenoma only, or with both serrated adenoma and advanced adenoma at index.
II [14]
The cumulative incidence of advanced serrated polyps at 1–5 years increased at a similar rate for patients with index serrated adenoma only (0.0–7.00%) and those with both serrated adenoma and non-advanced adenoma (0.0–11.00%).

For those with serrated adenoma with advanced adenoma, cumulative incidence of advanced serrated polyps remained steady at 9.00% from 2–5 years.

II [14]
There were no evidence to suggest statistically significant differences in the cumulative incidence of advanced serrated polyps over 1–5 years between patients with index features of sessile serrated adenomas <10mm, and those with hyperplastic polyp or sessile serrated adenoma ≥10mm, traditional serrated adenoma or sessile serrated adenoma with low-grade dysplasia (p=0.11). II [14]
Evidence-based recommendationA recommendation formulated after a systematic review of the evidence, indicating supporting references.Question mark transparent.png Grade
Sessile and traditional serrated adenomas (with or without conventional adenomas)

First surveillance intervals should be no greater than 5 years and should be based on features of synchronous conventional adenomas (if present) following complete removal of sessile and traditional serrated adenomas.

D
Consensus-based recommendationA recommendation formulated in the absence of quality evidence, after a systematic review of the evidence was conducted and failed to identify admissible evidence on the clinical question.Question mark transparent.png

Sessile and traditional serrated adenomas (with or without conventional adenomas)

First surveillance intervals should be based on the number, size and presence of dysplasia in the serrated polyps and synchronous conventional adenomas (if present) following complete removal of sessile and traditional serrated adenomas.


Clinically significant serrated polyps only
5 years for:

  • 1–2 sessile serrated adenomas all <10mm without dysplasia.

3 years for:

  • 3–4 sessile serrated adenomas, all <10mm without dysplasia
  • 1–2 sessile serrated adenomas ≥10mm or with dysplasia, or hyperplastic polyp ≥10mm
  • 1–2 traditional serrated adenomas, any size.

1 year for:

  • ≥5 sessile serrated adenomas <10mm without dysplasia
  • 3–4 sessile serrated adenomas, one or more ≥10mm or with dysplasia
  • 3–4 traditional serrated adenomas, any size.


Clinically significant serrated polyps and synchronous conventional adenomas
5 years for:

  • 2 in total, sessile serrated adenoma <10mm without dysplasia.

3 years for:

  • 3–9 in total, all sessile serrated adenomas <10mm without dysplasia
  • 2–4 in total, any serrated polyp ≥10mm and/or dysplasia
  • 2–4 in total, any traditional serrated adenoma.

1 year for:

  • ≥10 in total, all sessile serrated adenomas <10mm without dysplasia
  • ≥5 in total, any serrated polyp ≥10mm and/or dysplasia
  • ≥5 in total, any traditional serrated adenoma.


Synchronous high-risk conventional adenoma (tubulovillous or villous adenoma, with or without HGDHigh grade dysplasia and with or without size ≥10mm)
3 years for:

  • 2 in total, sessile serrated adenoma <10mm, without dysplasia
  • 2 in total, serrated polyp ≥10mm and/or dysplasia
  • 2 in total, any traditional serrated adenoma.

1 year for:

  • ≥3 total adenomas, sessile serrated adenoma any size with or without dysplasia
  • ≥3 total adenomas, one or more traditional serrated adenoma.
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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

Surveillance is recommended for ‘clinically significant’ serrated polyps:

  • sessile serrated adenomas
  • traditional serrated adenomas
  • hyperplastic polyps ≥10mm.
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

High-quality endoscopy is imperative to identify accurately and to completely remove sessile and traditional serrated adenomas and synchronous conventional adenomas.

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

PolypA small growth protruding from a mucous membrane, such as the lining of the bowel./adenoma size as per the endoscopist documentation should be used for determining surveillance intervals. All endoscopists should ensure size measurements are accurate using a reference standard (eg an open biopsy forceps or snare).

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Polyps removed should be submitted separately for histologic assessment to inform surveillance recommendations.

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

High-quality pathology interpretation is critical to correctly diagnose sessile and traditional serrated lesions and advanced serrated polyps.

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

High-quality reporting from endoscopists and pathologists is required to allow accurate risk stratification for surveillance interval recommendations.

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Surveillance intervals should be determined after the colon has been cleared of all significant neoplasia, once histology is known and in the context of individualised assessment of benefit to the patient.

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

Small, particularly distal, true hyperplastic polyps do not require surveillance.

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

Clinicians should be aware of the cumulative serrated polyp count and diagnostic criteria for serrated polyposis syndrome and recommend surveillance. See Clinical practice guidelines for the prevention, early detection and management of colorectal cancer, Serrated polyposis syndrome for diagnostic criteria and recommended surveillance.

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Notes on recommendations

The systematic review, although limited, demonstrated differences in the risk of metachronous neoplasia dependent on features of the SSAs and TSAs and the presence of synchronous conventional (tubular, tubulovillous and villous) adenomas, suggesting surveillance should occur within 5 years.

These recommendations are conservative, but prudence is warranted at present. The consensus-based recommendations to guide clinical practice are also informed by potentially prognostic features of serrated adenomas recognised in the general literature review:

  • The risk of MAAMetachronous advanced adenoma is increased when an individual has both SSA and high-risk conventional adenoma at baseline colonoscopy, compared with high-risk conventional adenomas alone.
  • The risk of metachronous SSA is much higher in those who have had an SSA alone, or SSAs synchronous with low or high risk conventional adenomas, than in those with conventional adenomas without SSAs at baseline colonoscopy.
  • The risk of metachronous ASPs seems to increase over time for those with SSA or TSATraditional serrated adenoma at baseline colonoscopy. Studies are underpowered to determine if the characteristics of serrated polyps at baseline can predict a clinically significant risk of metachronous advanced serrated polyps.
  • The risk of metachronous ‘advanced neoplasia’ including both advanced adenomas and ASPs seems to be higher in those with combined SSA and conventional adenomas at baseline.
  • There is variability in international guidelines with acknowledgement of the limited evidence base. Expert opinion regarding the importance of serrated polyps of large size, associated with dysplasia and multiplicity has led to these factors being incorporated into existing international guidelines.
  • Expert opinion recognises the unclear potential of large (≥10mm) hyperplastic polyps.
  • Expert opinion and some direct evidence supports increased surveillance when the number of serrated polyps meets the definition of serrated polyposis.

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Summary of recommendations for first surveillance intervals following removal of clinically significant serrated polyps (with or without conventional adenomas)


Table 9. Summary of recommendations for first surveillance intervals following removal of clinically significant serrated polyps (± conventional adenomas)

Table 9 1st surveillance removal serrated.PNGBack to top

Health system implications

Clinical practice

These guidelines are the first ever to separate conventional and serrated adenomas. There will be a learning curve for health care providers. The aim of the tables and colour-coding in this section is to facilitate transition from the old to new guidelines. An educational program and simple decision aids, such as wall charts and online decision tools, would help healthcare provider become familiar with the recommendations for surveillance intervals. These could be developed, promoted and distributed in conjunction with the relevant professional bodies and healthcare providers in the public and private domains.

The importance of high-quality endoscopy and pathology reporting cannot be overstated. Training and accreditation programmes should reflect these needs.

Resourcing

The resourcing implications of these guidelines are unclear but important to establish. There is likely to be an increased cost for pathologic assessment if a substantial proportion of health care providers currently do not submit all polyps removed for pathologic assessment or do not separate specimens.

Barriers to implementation

The main barrier for implementation of these recommendations will be dissemination across Australia and familiarisation for health care providers. This will be facilitated by a coordinated implementation and evaluation program.

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Summary of findings from studies reported in systematic review

Table 10. Findings of the studies reported in the systematic review
Study Design Outcome Baseline colonoscopy findings
Low-risk/

non-advanced conventional adenoma

High-risk/

advanced conventional adenoma

Isolated serrated polyps Combined serrated polyp and low-risk conventional adenoma Combined serrated polyp and high-risk conventional adenoma
Macaron 2015[14]

(USAUnited States of America)

Single centre retrospective

2004–2007

n=157

TSATraditional serrated adenoma 17/157=10.8%

Advanced adenoma NAANon-advanced adenoma (n=69) 6/69=8.7%

FU 56.9±16.7m 

AA (n=29) 6/29=20.7%

FU 34.3±20.8m

SPSerrated polyp* only (n=111)

3.86 (±1.39) Y

46.3±16.7m

6.31%

SPSerrated polyp with NAANon-advanced adenoma (n=30)

3.63 (±1.47) Y

43.6±17.6m

6.67%

SPSerrated polyp with AA (n=16)

1.98 (±1.41) Y

23.8±16.9m

18.75%

Advanced serrated polyps 1/69=1.4% 0/29=0% 6/111=5.4% 3/30=10% 2/16=12.5%
Pereyra 2016[12]

(Argentina)

Single centre prospective 4/2007–12/2009

n=75 SPs

Advanced neoplasia NAANon-advanced adenoma (n=140) 11/140=7.9%

FU 53.96m

AA (n=87) 20/87=23%

FU 45.32m

SSA only (n=47)

4 (±1.17) Y 45.36m

3/47=6.4%

SSA with LRALow risk adenoma (n=14)

4 (±1.17) Y 49.85m

0/14=0%

SSA with HRAHigh risk adenoma (n=14)

4 (±1.17) Y 46.42m

7/14=50%

RRRelative risk 4.88 (1.05–26.9, p=0.02)

Melson 2016[13]

(USAUnited States of America)

Single centre retrospective 1/2005 -12/2011

n=166

^TSATraditional serrated adenoma 6/166=3.6% (excluded in MANMetachronous advanced neoplasia analysis)

“Advanced neoplasia”

3 CRCColorectal cancer

LRALow risk adenoma (n=370) 29/370=7.8%

FU 53.9±22.1m

CRCColorectal cancer 2 (6.9%)

HRAHigh risk adenoma (n=252) 40/252=15.9% 40.1±20.9m SSA^ only (n=106)

26/106=24.5%

Low risk SPSerrated polyp only 10/56=17.9% (p=0.024)

High risk SPSerrated polyp only 16/50=32%

LRALow risk adenoma including SSAs: (n=66)

FU 3.94 (±1.39) 47.3±16.7m

12/66=18.2% (p=0.019)

LRALow risk adenoma with SSA

2/10=20%

HRAHigh risk adenoma including SSAs (n=94)

FU 3.54 (±1.43) 42.5±17.2m

n=94

30/94=31.9%

CRCColorectal cancer 1 (1/94=3.3%)

HRAHigh risk adenoma with SSA

14/44=31.8%

SSA LRALow risk adenoma 16/370=4.3% HRAHigh risk adenoma 15/252=6.0% 22/66=33.3% (p=0.001) 31/94=33.0% (p=0.001)
*SPSerrated polyp at baseline: SSA±dysplasia, TSATraditional serrated adenoma, HP≥10mm AA: ≥10mm/villous/HGDHigh grade dysplasia NAANon-advanced adenoma: <10mm without HGDHigh grade dysplasia or villosity; ASPAdvanced serrated polyp: SSA or HP ≥10mm, SSA with dysplasia or TSATraditional serrated adenoma of any size; High-risk SPSerrated polyp: TSATraditional serrated adenoma and SSA with dysplasia LRALow risk adenoma with SSAs – included either a low-risk SSA and a low-risk adenoma or only a low-risk SSA; LRALow risk adenoma only included 1–2 TA <10mm without dysplasia.

AA: advanced adenoma; ASPAdvanced serrated polyp: advanced serrated polyp; CRCColorectal cancer: colorectal cancer; HRAHigh risk adenoma: high-risk adenoma; LRALow risk adenoma: low-risk adenoma; m: months; MANMetachronous advanced neoplasia: metachronous advanced neoplasia; NAANon-advanced adenoma: non-advanced adenoma; SPSerrated polyp: serrated polyp; SSA: sessile serrated adenoma; TSATraditional serrated adenoma: traditional serrated adenoma; Y: years.

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International guidelines for surveillance after removal of serrated polyps at baseline colonoscopy


Table 11. International guidelines for surveillance after removal of serrated polyps at baseline colonoscopy
Guideline Serrated PolypA small growth protruding from a mucous membrane, such as the lining of the bowel. Category
HP SSA TSATraditional serrated adenoma SPSerrated polyp Associated

conventional adenoma

Location Sized <5mm 5–9mm ≥10mm Dysplasia Sized <10mm Sized ≥10mm Sized <10mm Sized ≥10mm
Cancer Council Australia (2011)[1] Any No surveillance N/A N/A 1 Y N/A
BSGBritish Society of Gastroenterology (2017)[3] Any No surveillance 3 Y 3 Y No surveillance 3 Y 3 Y 1 Y Consider each

group separately

ESGEEuropean Society for Gastroenterology (2013)[18] Any Screening or 10 Y 3 Y 3 Y Screening or 10 Y 3 Y Screening

or 10 Y

3 Y N/A N/A
US consensus panel (2012)[19] Proximal to sigmoid 10 Y if ≤3

5 Y if ≥4

5 Y 5 Y 1–3 Y 5 Y if 1–2

3 Y if ≥3

3 Y

1-3 Y if ≥2

5 Y if 1-2 3 Y 1 Y N/A
Distal 10 Y 10 Y
USMTFUS Multi-Society Task Force/AGAAmerican Gastroenterological Association (2012)[22] Proximal to sigmoid 3 Y 5 Y if 1

3 Y if ≥2

3Y 3 Y 3 Y 1 Y N/A
Distal
European (2010)[23] 10 Y if distal to rectosigmoid 10 Y

1–3 Y if ≥3

3 Y NR N/A
HP: Hyperplastic polyp; N/A: non-applicable; NR: not recorded; SPs: serrated polyp;Y: years. SSAs: sessile serrated adenoma; TSATraditional serrated adenoma: traditional serrated adenoma.
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References

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Appendices

Jutta's magnifying glass icon.pngPICO question SAD 4 View Evidence statement form SAD4Evidence statement form SAD4 View Systematic review report SAD4Systematic review report SAD4
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