- 1 Definition
- 2 Background
- 3 Evidence
- 4 Evidence summary and recommendations
- 5 Health system implications
- 6 References
- 7 Appendices
Patients in whom ≥5 conventional (tubular, tubulovillous or villous) adenomas have been detected and removed are in a separate risk category from those with fewer adenomas. For surveillance intervals following removal of ≥5 conventional adenomas with synchronous clinically significant serrated polyps see First surveillance intervals following removal of serrated polyps (± conventional adenomas)
In the 2011 Australian clinical practice guidelines for surveillance colonoscopy, a surveillance interval of 1 year (5–9 adenomas) or within a year (≥10 adenomas) was recommended for individuals following the removal of ≥5 conventional adenomas at the index colonoscopy. Although the association of risk for metachronous advanced adenomaAn adenoma that measures 10mm or more in size. Includes adenomatous polyps greater than or equal to 10 mm in size or with a significant villous component or with high-grade dysplasia. (MAA) and increasing numbers of adenomas detected and removed at index colonoscopy remains, in the era of high quality endoscopy, the magnitude of this risk may not be as great as previously.
What should be the surveillance interval following removal of ≥5 conventional adenomas only? [SAD5]
Systematic review evidence
The systematic review reported outcomes from three level III-2 studies. One was at low and two at moderate risk of bias. Two studies were from Korea and the third from the USA, with a marked over-representation of males. Overall, although the evidence may not be directly generalisable, it could probably be sensibly applied to the Australian healthcare environment. In general, reported outcomes included metachronous adenomas (MA), metachronous advanced adenomas (MAA), metachronous colorectal cancers (CRC), metachronous advanced neoplasia (MAN) and metachronous neoplasia (MN) at follow-up of around 3 and 5 years. The three studies had different inclusions, thus limiting direct comparisons (see Table 6). There were no reports of long-term outcomes. In all studies, metachronous CRC was uncommon with a risk of 0–0.8% in those with both 5–9 and ≥10 adenomas. The risk of MAA varied according to the number and other index adenoma features such as size and follow-up duration. The risk of MAA repotred in these studies was:
- 5% in those with at least 5 adenomas all <10mm of any histology (n=169) after 3 years follow-up
- 9.1% for those with 5–9 non-advanced adenomas removed at index colonoscopy (n=99) after a mean follow-up of 4 years
- 11.9% for those with 3–10 adenomas (>60% advanced) removed at index colonoscopy (n=975) after a mean follow up of 4.0 years
- 16.3% in those with at least 5 adenomas with 1 ≥10mm (n=123) after 3 years follow-up
- 26.6% in those with >10 adenomas (>60% advanced) removed at index colonoscopy (n=214) after a mean follow-up of 4.3 years.Back to top
Overview of additional evidence (non-systematic literature review)
Metachronous advanced neoplasia according to size of prior adenomas removed
One level III-2 study investigated MAN after the removal of 3–9 non-advanced adenomas at index colonoscopy according to size (n=130). The incidence of MAN was 6.3% in the group with 3–9 adenomas sized 1–5mm (n=79) and 9.8% in the 3–9 adenomas sized 6–9mm (n=51) with a median follow-up of 32 months (interquartile range 13–48).
Table 6. Summary of studies with ≥5 adenomas – metachronous neoplasia
|Author and design||n||Patient group at index colonoscopy||Outcome and follow-up time|
|Advanced adenomaAn adenoma that measures 10mm or more in size. Includes adenomatous polyps greater than or equal to 10 mm in size or with a significant villous component or with high-grade dysplasia.||CRC||Advanced neoplasia|
|0%||AR 3Y||AR 5Y|
60% advanced adenomas
|0.1%||AR 3Y||AR 5Y|
68.2% advanced adenomas
Secondary analysis of a database
|0.6%||5% (1068 days, SD 529)|
at least one ≥10mm,
|0.8%||16.3% (737 days, SD 553)|
1–9mm with LGD
|n||Patient group at index colonoscopy||Follow up years||Incidence/rate per 1000/per annum
HR (95% CI)
|Abbreviations: AR: absolute riskThe risk a subject has for developing the tested disease over a stated time period.; CRC: colorectal cancer; HR: hazard ratioA measure of how often a particular event happens in one group compared to how often it happens in another group, over time.; LGD: low grade dysplasia; SD: standard deviation; NA: not applicable NAA: non advanced adenomaAn adenoma that measures 10mm or more in size. Includes adenomatous polyps greater than or equal to 10 mm in size or with a significant villous component or with high-grade dysplasia.; Y: years.|
Expert opinion and clinical practice guidelines from other countries
International recommendations demonstrate considerable variability (Table 7) and Table 4 Summary of international surveillance guidelines).
Table 7. International recommendations for multiple adenomas
|International recommendation||Adenoma description||Recommended surveillance interval|
|American Gastroenterological Association||3–10 tubular adenomas||3 years|
|>10 adenomas||<3 years|
|British Society of Gastroenterology||≥5 adenomas||1 year|
|Canadian Association of Gastroenterology||3–10 tubular adenomas||3 years|
|>10 adenomas||<3 years|
|European Society of Gastroenterology)||≥3 adenomas||3 years|
|New Zealand||≥5 adenomas||1 year|
Evidence summary and recommendations
|In patients with 5–9 non-advanced adenomas at index colonoscopy, metachronous neoplasia was detected in almost 80% of patients at follow-up of 4.0±1.5 years. In the same group of patients, 100% had developed metachronous neoplasia at 6–7 years after index colonoscopy.||III-2|||
|In a group of 214 patients with >10 adenomas at index (14.2 ± 0.3 adenomas; 68.2% with advanced adenomas at index) neoplasia was detected in almost 90% of patients after a mean follow-up of 4.3 years. In the same group, metachronous neoplasia was detected in 100% of patients 8 years after index colonoscopy.||III-2|||
|In patients with 5–9 non-advanced adenomas at index (n=99), metachronous advanced adenomaAn adenoma that measures 10mm or more in size. Includes adenomatous polyps greater than or equal to 10 mm in size or with a significant villous component or with high-grade dysplasia. was reported in 9.1% after a mean follow-up of 4 years.||III-2|||
|In patients with >10 adenomas at index (14.2±0.3 adenomas, 68.2% with advanced adenomas at index, n=214), metachronous advanced adenomas were reported in 26.6% after a mean follow-up of 4.3 years.||III-2|||
|The risk of metachronous advanced neoplasia was similar to that of advanced adenomas, and was 16.3% after 3 years of follow-up.||III-2|||
|Only one case of metachronous colorectal cancer was reported across two studies (n=551) in patients with no advanced adenomas at index.||III-2||, |
|Only one case of metachronous colorectal cancer was reported across two studies (n=1312) in patients with advanced adenomas at index.||III-2||, |
|Those with at least 5 adenomas with one ≥10mm had a detection rate of 2.4%, compared to no findings in those with 5 adenomas all ≤10mm, after 3 years follow-up.||III-2|||
|Those with at least 5 adenomas with 1 ≥10mm had a detection rate of MAN of 1.6%, compared to 0.6% in those with 5 adenomas all ≤10mm at index, after 3 years follow-up||III-2|||
|Those with at least 5 adenomas with 1 ≥10mm had a detection rate of 11.4% for tubular adenoma ≥10mm verse 3.7% for those with 5 adenomas all ≤10mm at index.||III-2|||
|Absolute riskThe risk a subject has for developing the tested disease over a stated time period. of metachronous advanced adenomaAn adenoma that measures 10mm or more in size. Includes adenomatous polyps greater than or equal to 10 mm in size or with a significant villous component or with high-grade dysplasia. was reported in one study in patients with 5–9 non-advanced adenomas at index (n=99) at 3 years (AR=1.2%, CI=1.17–1.22) and 5 years (AR=6.4%, CI=6.34–6.46) follow-up. In another study it was reported that the risk of metachronous advanced adenomas in those patients with at least 5 adenomas all <10mm at index (OR=3.1, CI 1.2–8.2, p=0.021) with 1068±529 days follow-up.||III-2||, |
|At follow-up of 737±553 days after index colonoscopy, the risk of metachronous advanced neoplasia was significantly greater in patients with at least 5 adenomas with 1 ≥10mm, than in those with 1–2 adenomas all < 10mm (OR=10.8, CI=4.5-25.7, p<0.001).||III-2|||
|In a single study that reported outcomes in patients with >10 adenomas, the risk of metachronous neoplasia at follow-up of 4.3±1.5 years was significantly higher in those with >10 adenomas at index colonoscopy than in those with 3–10 adenomas at index colonoscopy (odds ratioA comparison of the odds (probability) of something happening in one group with the odds of it happening in another. 3.46; 95% CI 1.90–6.28).||III-2|||
|In a single study that separately reported the rate of metachronous advanced adenomas, the risk at follow-up of 4.3±1.5 years was higher in those with >10 adenomas at index colonoscopy than in those with 3–10 adenomas at index colonoscopy (odds ratioA comparison of the odds (probability) of something happening in one group with the odds of it happening in another. 2.25; 95% CI 1.49–3.38).||III-2|||
≥5 conventional adenomas only
First surveillance intervals following complete removal of ≥5 conventional adenomas only, should be no longer than 3 years.
≥5 conventional adenomas only
First surveillance intervals should be within 3 years and stratified based on the number, size and histology following complete removal of ≥5 adenomas only.
For those with ≥10 adenomas, the recommended surveillance interval is 1 year, regardless of size or histology.
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.
Consistently high-quality colonoscopy is imperative for optimal cost effectiveness and for implementation of uniform surveillance guidelines.
Polyp/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).
Polyps removed at colonoscopy should be sent separately for histology to guide surveillance recommendations.
Clinicians should accurately record adenoma features relevant to surveillance intervals so that individualised surveillance recommendations can be made.
An underlying familial predisposition to colorectal cancer should be considered in all individuals with ≥10 polyps removed. Referral to a familial cancer clinic should be considered, along with appropriate psychological support.
Separate screening and surveillance recommendations apply to patients with diagnosed or likely familial syndromesGenetic disorders in which inherited genetic mutations in one or more genes predispose a person to developing cancer, particularly at an early age. (see Should family history affect surveillance intervals?).
Notes on the recommendations
The systematic review supported surveillance within 3 years following removal of ≥5 conventional adenomas but did not offer guidance on intervals within this broad timeframe. General review of the literature offered further information to guide clinical practice and inform the current recommendations which are consistent with international guidelines.
The recommendations are based on the expectation that endoscopists in Australia are performing high quality colonoscopy with complete adenoma excision and are supported by accurate pathology reporting.
Table 3. Summary of recommendations for first surveillance intervals following removal of conventional adenomas only Back to top
Health system implications
These surveillance guidelines will result in substantial change to which health care providers will need to adjust. The aim of Table 3 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 management of surveillance following removal of adenomas is critical in terms of health outcomes, demand for colonoscopy and cost. Recently, the Cancer Research Division, Cancer Council NSW used the Australian developed and validated model Policy1-Bowel to compare the new and previous surveillance guidelines specifically related to the National Bowel Cancer Screening Program. Preliminary results demonstrate comparable health outcomes, reduced number of surveillance colonoscopies and similar program-related costs (see the preliminary results report on Modelled comparison of proposed surveillance recommendations for the NBCSP). 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 healthcare providers. This will be facilitated by a coordinated implementation and evaluation programme.
- Cancer Council Australia Colonoscopy Surveillance Working Party. Clinical Practice Guidelines for Surveillance Colonoscopy – in adenoma follow-up; following curative resection of colorectal cancer; and for cancer surveillance in inflammatory bowel disease. Sydney: Cancer Council Australia; 2011 Dec.
- Vemulapalli KC, Rex DK. Risk of advanced lesions at first follow-up colonoscopy in high-risk groups as defined by the United Kingdom post-polypectomy surveillance guideline: data from a single U.S. center. Gastrointest Endosc 2014 Aug;80(2):299-306 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/24796960.
- Park SK, Song YS, Jung YS, Kim WH, Soo Eun C, Ko BM, et al. Do surveillance intervals in patients with more than five adenomas at index colonoscopy be shorter than those in patients with three to four adenomas? A Korean Association for the Study of Intestinal Disease study. J Gastroenterol Hepatol 2017 May;32(5):1026-1031 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/27862272.
- Park SK, Hwang SW, Kim KO, Cha JM, Boo SJ, Shin JE, et al. Risk of advanced colorectal neoplasm in patients with more than 10 adenomas on index colonoscopy: A Korean Association for the Study of Intestinal Diseases (KASID) study. J Gastroenterol Hepatol 2017 Apr;32(4):803-808 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/27785837.
- Sneh Arbib O, Zemser V, Leibovici Weissman Y, Gingold-Belfer R, Vilkin A, Eizenstein S, et al. Risk of advanced lesions at the first follow-up colonoscopy after polypectomy of diminutive versus small adenomatous polyps of low-grade dysplasia. Gastrointest Endosc 2017 Mar 8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/28284884.
- Lieberman DA, Rex DK, Winawer SJ, Giardiello FM, Johnson DA, Levin TR. Guidelines for colonoscopy surveillance after screening and polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology 2012 Sep;143(3):844-857 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/22763141.
- Cairns SR, Scholefield JH, Steele RJ, Dunlop MG, Thomas HJ, Evans GD, et al. Guidelines for colorectal cancer screening and surveillance in moderate and high risk groups (update from 2002). Gut 2010 May;59(5):666-89 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/20427401.
- Leddin D, Enns R, Hilsden R, Fallone CA, Rabeneck L, Sadowski DC, et al. Colorectal cancer surveillance after index colonoscopy: guidance from the Canadian Association of Gastroenterology. Can J Gastroenterol 2013 Apr;27(4):224-8 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/23616961.
- New Zealand Guidelines Group. Colorectal cancer: Management of Early Colorectal Cancer. Wellington: Ministry of Health; 2011.
- Lew JB, St John DJB, Xu XM, Greuter MJE, Caruana M, Cenin DR, et al. Long-term evaluation of benefits, harms, and cost-effectiveness of the National Bowel Cancer Screening Program in Australia: a modelling study. Lancet Public Health 2017 Jul;2(7):e331-e340 Abstract available at http://www.ncbi.nlm.nih.gov/pubmed/29253458.
|PICO question SAD 5||Evidence statement form SAD5||Systematic review report SAD5|