- 1 Definition
- 2 Background
- 3 Evidence
- 3.1 Systematic review evidence
- 3.2 Overview of additional evidence (non-systematic literature review)
- 3.2.1 Long-term outcomes
- 3.2.2 Influence of high-risk features (size ≥10mm, HGD, villosity, 3-4 adenomas)
- 220.127.116.11 Size
- 18.104.22.168 High-grade dysplasia
- 22.214.171.124 Villosity
- 126.96.36.199 Multiplicity
- 188.8.131.52 3–4 small adenomas or 1–2 adenomas with one ≥10mm without advanced histologic features
- 184.108.40.206 Cumulative risk in patients with multiple high-risk factors detected
- 220.127.116.11 Expert opinion and clinical practice guidelines from other countries
- 4 Evidence summary and recommendations
- 5 Health system implications
- 6 Colorectal cancer incidence and mortality after adenoma removal
- 7 References
- 8 Appendices
Individuals at high risk are those who have had one or more conventional (tubular, tubulovillous or villous) adenomas removed at the baseline colonoscopy with one or more of the following four features:
- size ≥10mm*
- high-grade dysplasia (HGDHigh grade dysplasia)
- 3–4 adenomas.
*Adenomas ≥20mm are more likely to be excised piecemeal. For surveillance intervals for patients following removal of adenomas ≥20mm, see First surveillance intervals following removal of large sessile or laterally spreading adenomas.
For surveillance intervals for patients following removal of ≥5 conventional adenomas, see First surveillance intervals following removal of ≥5 conventional adenomas only (SAD5).
For surveillance intervals for clinically significant serrated polyps with or without synchronous conventional adenomas, see First surveillance intervals following removal of serrated polyps (± conventional adenomas).
The 2011 edition of this guideline recommended surveillance at 3 years for individuals following removal at baseline colonoscopy of adenomas with any of the following characteristics: size ≥10mm, HGDHigh grade dysplasia, villosity, 3–4 adenomas. The 2018 recommendations are based on systematic review, non-systematic review of relevant literature, international recommendations and expert opinion.
What should be the first surveillance interval following removal of high-risk conventional adenomas only (size ≥10mm, HGDHigh grade dysplasia, villosity and/or 3-4 adenomas)? [SAD2]
Systematic review evidence
The systematic review included studies published since 2010 of colonoscopic procedures performed from 2002.
Four level II prospective and ten level III-2 retrospective cohort studies were included. Nine studies had a high risk of bias and five studies had a moderate risk of bias. Outcomes reported included incidence and risk of metachronous colorectal cancer (CRCColorectal cancer), metachronous adenoma (MAMetachronous adenoma) and metachronous advanced adenoma (MAAMetachronous advanced adenoma). Surveillance intervals ranged from less than 3 years to 3–5 years. None of the included studies reported follow up at 10 years or CRCColorectal cancer mortality. Most studies consistently reported the risk of metachronous colorectal cancer and MAMetachronous adenoma. The reporting of MAAMetachronous advanced adenoma was more variable. The evidence was probably generalisable to the Australian population and applicable to the Australian healthcare system with some caveats.
At variable surveillance intervals less than 3 years and between 3–5 years:
- IncidenceAn epidemiological term reporting number of new cases in a population within a specified period. of metachronous CRCColorectal cancer ranged from 0–1.52%
- IncidenceAn epidemiological term reporting number of new cases in a population within a specified period. of MAAMetachronous advanced adenoma varied within the range of 2.40–24.24%
The evidence base is limited for outcomes in individuals after removal of high-risk adenomas, particularly high-quality studies with long-term outcomes using modern endoscopy techniques.
Overview of additional evidence (non-systematic literature review)
Five level III-2 studies reported long-term CRCColorectal cancer incidence and mortality following adenoma removal in high-risk groups (Table 5) but were not included in the systematic review as they did not fit the criteria, particularly as they included colonoscopies performed prior to 2002.
Three level III-2 studies reported long-term CRCColorectal cancer incidence:
- Cottet et al reported on a French retrospective cohort (n=5779). Participants had incident high-risk adenomas removed between 1990 and 1999 and were followed up using registry data until 31/12/2003, for a median of 7.7 years (interquartile range [IQR] 5.2–10.5). The overall standardised incidence ratio (SIRStandardised incidence ratio) of CRCColorectal cancer was 2.23 (1.67–2.92): 1.10 (0.62–1.82) with surveillance colonoscopy and 4.26 (2.89–6.04) without. The 10-year cumulative incidence of CRCColorectal cancer was 2.05% (1.14–3.64) with and 6.22% (4.26–9.02) without surveillance colonoscopy.
- Brenner et al performed a large case-control study in Germany, identifying cases of CRCColorectal cancer (n=2582) and controls (n=1798) from the population registry matched for age, sex and location. Patients who had had a colonoscopy with removal of a polyp with high-risk features had a reduced adjusted odds ratio (OR) of CRCColorectal cancer at any site, proportional to time since polypectomy: 0.3 (0.3–0.7) for <3 years, 0.5 (0.3–0.8) for 3–5 years and 1.1 (0.5–2.6) for 6–10 years, compared to no colonoscopy (OR 1.0).
- Atkin et al looked at long-term incidence of CRCColorectal cancer in those with 3–4 small adenomas and 1–2 adenomas at least one of which was ≥10mm (n=11,944) and compared it to age- and sex-standardised incidence from the general population. Years of entry were 1990–2010, with censoring in 2014 and median follow-up of 7.9 years (IQR 5.6–11.1). After adjustment for baseline risk factors, CRCColorectal cancer incidence in the whole cohort was not significantly different from that of the general population (SIRStandardised incidence ratio 1.09, 95% confidence interval [CI] 0.91–1.30). Compared with no surveillance (hazard ratio [HR] 1), one surveillance visit at median 2.9 years (IQR 1.3–3.4) was associated with a significant reduction in colorectal cancer incidence (HR 0.57, 95% CI 0.40–0.80), two visits HR 0.51 (0.31–0.84) and three or more visits HR 0.54 (0.29–0.99); p=0.0029 for any surveillance visit, compared with no surveillance.
Two level III-2 studies reported CRCColorectal cancer-specific mortality:
- Zauber et al compared CRCColorectal cancer-specific mortality in participants (n=2602) who had adenomatous polyps removed in the US National PolypA small growth protruding from a mucous membrane, such as the lining of the bowel. Study between 1980 and 1990 with standardised incidence-based CRCColorectal cancer-specific mortality in the general population using Surveillance Epidemiology and End Results (SEERSurveillance, Epidemiology and End Results) data. Patients with low- and high-risk adenomas were included, with 57.3% advanced adenomas and 19.3% ≥3 adenomas. Median follow-up was 15.8 years, with maximum of 23 years. Overall, standardised mortality ratio (SMRStandardised mortality ratio) was 0.47 (0.26–0.80). The risk of CRCColorectal cancer mortality of those with adenomas removed was the same as those with non-adenomatous polyps at 10 years. Cumulative CRCColorectal cancer-specific mortality at 20 years was 0.8% for the National PolypA small growth protruding from a mucous membrane, such as the lining of the bowel. Study patients versus 1.5% in the general population. Mortality reduction was similar for the first 10 years of follow-up at 0.44 (0.14–1.06, p=0.09) compared with 10 or more years at 0.49 (0.23–0.93, p=0.04).
- Løberg et al followed n=40,826 individuals after adenoma removal during 1993–2007 and compared CRCColorectal cancer-specific mortality with the general population up to 2011, with a median follow-up of 7.7 years (maximum 19 years). As per Norwegian Guidelines, a surveillance of 10 years is recommended for those with high-risk adenomas. The CRCColorectal cancer-specific SMRStandardised mortality ratio was 1.16 (1.02–1.31).
Influence of high-risk features (size ≥10mm, HGDHigh grade dysplasia, villosity, 3-4 adenomas)
Size distinguishes low risk (<10mm) and high risk (≥10mm) for metachronous adenoma (MAMetachronous adenoma), with further division more recently into adenomas of 6–9mm (small) and 1–5mm (diminutive). Size correlates with advanced histology (villosity and/or HGDHigh grade dysplasia).A recent review highlights the variability in the literature but summarises findings as “adenoma size ≥10mm appears to be associated with future advanced neoplasia and the magnitude of risk increases for larger adenomas ≥20mm in size.” A meta-analysis reported an OR for metachronous neoplasia (MNMetachronous neoplasia) of 2.24 (1.4–3.59) comparing various smaller adenomas with those ≥10mm, generally at median follow-up intervals between 17 months and 16 years. On multivariate analysis, Atkin et al found that adenoma size 10–19mm (HR 1.97; 1.01–3.81) and ≥20mm (HR 2.28; 1.16–4.50) was associated with increased incidence of CRCColorectal cancer when compared with <10mm, at median follow-up of 7.9 years. Potential difficulty in interpreting the literature may arise from inconsistency in the measurement of adenoma size, which has been shown to be inconsistent among endoscopists.
The question of whether HGDHigh grade dysplasia is associated with MNMetachronous neoplasia has been challenged by histologic consistency of reporting, separating the influence of size and villosity and population heterogeneity. Accordingly, the British guidelines do not incorporate HGDHigh grade dysplasia when considering surveillance intervals. Despite some variability, recent literature indicates an independent association between HGDHigh grade dysplasia and MNMetachronous neoplasia. A meta-analysis reported a multivariate relative risk (RRRelative risk) of 2.04 (1.10–3.78) for HGDHigh grade dysplasia in the index adenoma predicting MNMetachronous neoplasia at median follow-up between 17 months and 16 years. Facciorusso et al reported a multivariate OR of 4.25 (2.11–7.5) for MAAMetachronous advanced adenoma at 3 years, whereas van Heijningen et al reported a RRRelative risk for metachronous advanced neoplasia (MANMetachronous advanced neoplasia) of 1.9 (1.3–2.7) on univariate but 1.3 (0.9–1.9) on multivariate analysis at median follow up of 35 months. Taniguchi reported an OR 2.4 (1.51–3.83) for HGDHigh grade dysplasia versus low-grade dysplasia (LGDLow grade dysplasia) in the largest adenoma for MAMetachronous adenoma at follow up within 2 years on multivariate analysis. Another systematic review reported a small and variable association of HGDHigh grade dysplasia with risk of metachronous advanced neoplasia in a systematic review. Most recently, Atkin et al found a HR of 1.69 (1.21–2.36) for HGDHigh grade dysplasia versus LGDLow grade dysplasia for incident CRCColorectal cancer following removal of intermediate risk adenomas at median follow-up of 7.9 years. High-grade dysplasia is less common in diminutive polyps, with an incidence of around 0.1–0.3%, and 0.3–0.8% in small adenomas. The metachronous neoplasia risk is unclear, but is likely to be low.
VillosityThe state of being villous, a histopathological feature of some tubular adenomas. Villous adenoma is a type of polyp found in the colon or rectum that appear as a cauliflower-like mass.
The association of villosity with MNMetachronous neoplasia has been complicated by factors that make it difficult to compare outcomes between studies. These include variability in histologic diagnosis (the change in the World Health Organization definition in 2010 of 'villosity' from 20% to 25% villous component being particularly relevant), and different outcome definitions (sometimes tubulovillous and villous, at other times one or the other). Differing length of follow-up may also partially explain variation. Such is the uncertainty about the significance of villosity, that the British guidelines do not incorporate villosity when considering surveillance intervals.
Recent literature generally indicates that villosity is an independent predictor for MNMetachronous neoplasia. A meta-analysis reported a multivariate-adjusted OR 1.77 (1.16–2.71) for MNMetachronous neoplasia at median follow-up of between 17 months and 16 years, whilst another concluded that villous histology within an adenoma may have a small association with future advanced neoplasia but this was not seen uniformly across all studies. In individual studies:
- Facciorusso et al reported an OR for MAAMetachronous advanced adenoma of 1.49 (0.47–5.18) on univariate analysis and 1.73 (0.68–4.45) on multivariate analysis at 3 years.
- Taniguchi reported an OR of 2.07 (1.59–2.70) on univariate analysis but 1.56 (0.98–2.52) on multivariate analysis at follow-up within 2 years.
- van Heijningen found villous histology significant on univariate and multivariate analysis at follow-up intervals of between less than 4 years and more than 6 years, with an OR of 2.3 (1.4–3.6).
- Atkin et al did not find villosity to be associated with metachronous CRCColorectal cancer, with a HR of 1.16 (0.71–1.91) on multivariate analysis at median 7.9 years follow-up.
Increasing number of adenomas at baseline is associated with MNMetachronous neoplasia. A recent meta-analysis reported a RRRelative risk of 2.32 (95% CI 1.81, 2.98) when comparing 1 to ≥2 baseline adenomas. An often-quoted large study of pooled trial data from 2009 described a relatively high risk of MAAMetachronous advanced adenoma within 3–5 years at 8.6%, 12.7%, 15.2%, 19.6% and 24.1% for one, two, three, four and five adenomas, respectively. Of note, the included trials recruited from the 1980s and 1990s in the era of lower quality colonoscopy.
More recent studies have shown much lower rates of MAAMetachronous advanced adenoma. In one study the incidence of MAAMetachronous advanced adenoma was 5.8% following removal of 3–4 non-advanced adenomas at baseline colonoscopy (n=291) at 4.0±1.3 years. Another showed the incidence of MAAMetachronous advanced adenoma to be 3.5% after removal of 1–2 diminutive adenomas, compared with 6.3% after 3–9 diminutive adenomas; and 9.8% following removal of both 1–2 and 3–9 small (6-9mm) adenomas at a median of 32 months (IQR 13–48). In another study, the risk of MAAMetachronous advanced adenoma was 11.9% in patients with 3–10 adenomas after follow-up of 4.0 years.
Although the relationship between number at baseline colonoscopy and MNMetachronous neoplasia is consistent across most literature, Atkin et al demonstrated a non-significant (p=0.12) multivariate HR of 0.58 (95% CI 0.31–1.11) for 3 or 4 adenomas compared to 1, perhaps suggesting an effect of higher quality colonoscopy with the detection of more adenomas.
3–4 small adenomas or 1–2 adenomas with one ≥10mm without advanced histologic features
Several recent papers have investigated at whether, following removal of high-risk adenomas, a sub-group of patients may be at lesser risk. In the first study, institutional data from 2002–2012 were analysed, finding a 1.8% risk of MAAMetachronous advanced adenoma following removal of 3–4 adenomas all less than 10mm; compared with a risk of 8.6% at a mean of 3.28±1.75 years, when the size of at least one adenoma was ≥10mm.
In the second study, Atkin et al assessed long-term outcomes of standardised CRCColorectal cancer incidence against a population reference in patients following removal of 3–4 small adenomas or 1–2 adenomas, one of which was ≥10mm (these included advanced histologic features as per British guidelines). ColorectalReferring to the large bowel, comprising the colon and rectum. cancer incidence in these patients, regardless of follow-up, was not significantly different from that of the general population (SIRStandardised incidence ratio 1.09, 95% CI 0.91–1.30).
A retrospective, multicentre cohort study included patients recruited between 2007 and 2008 with ≥3 adenomas or one or more adenomas ≥10mm, stratified according to the British Guidelines. In the group with 3–4 non-advanced adenomas (n=291), at 4.0±1.3 years the incidence of MAAMetachronous advanced adenoma was 5.8% and CRCColorectal cancer 0.3%.
Cumulative risk in patients with multiple high-risk factors detected
Several groups have recently looked at the impact of multiple high-risk findings. A group from Korea retrospectively (2005–2009) analysed data for 862 individuals, with high-risk factors: size ≥10mm, HGDHigh grade dysplasia, villosity and ≥3 adenomas. The cumulative incidence of MANMetachronous advanced neoplasia was associated with the number of high-risk findings. At 5 years, MANMetachronous advanced neoplasia rates were 8.5% with no high-risk findings, 18.7% with one, 26.3% with two, and 37.2% with three or four high-risk findings, with the number needed to treat to find a single MAAMetachronous advanced adenoma at 3 years being 8.4, 6.5 and 4.1 for one, two and three to four factors, respectively. At 1 and 2 years for those with three to four factors, needed to treat was 12.5 and 6.6, respectively.
A Japanese group combined metabolic factors (age ≥65 years, BMIBody mass index>25, fasting blood glucose >126 mg/dL) and adenoma predictors (HGDHigh grade dysplasia, villosity, right sided location, largest adenoma diameter ≥10mm, number removed ≥3) into a risk score from 0–10 points. The risk of adenoma recurrence increased as the risk score increased, with an OR of 7.07 for those with a score of 0–2 compared with those with a score of 3–10 (95% CI 5.30–9.43).
van Heijningen et al developed a simple risk score from 0 to 5 which was predictive of MANMetachronous advanced neoplasia and incorporated into the Dutch Surveillance Guidelines. The score consists of characteristics contributing 1 point (size ≥10mm, villous histology, proximal location, having 2–4 adenomas) or 2 points (having ≥5 adenomas). Although not yet externally validated, the score has been modelled with a c-statistic of 0.71, which is better than that of the British Society of Gastroenterology (BSGBritish Society of Gastroenterology) (2010) guidelines (0.674; 0.634–0.713) and American Gastroenterological Association (AGAAmerican Gastroenterological Association) (2012) guidelines (0.664; 0.625–0.703).
The risk for diminutive adenomas with advanced histologic features is poorly defined but seems low. Such adenomas are very rare.
Expert opinion and clinical practice guidelines from other countries
The definition of ‘high risk’ varies amongst clinical practice guidelines from other countries, with previous Australian guidelines having both moderate- and high-risk categories. Similarly, in the BSGBritish Society of Gastroenterology, European and New Zealand guidelines, 3–4 adenomas are split from ≥5 adenomas, with the BSGBritish Society of Gastroenterology and NZ guidelines including 3–4 adenomas with at least one ≥10mm in the highest risk category.
A comparison of the AGAAmerican Gastroenterological Association versus BSGBritish Society of Gastroenterology guidelines using pooled trial data showed a risk of MANMetachronous advanced neoplasia at 1 year of 18.7% (14.8–22.5%) in this highest risk group. By contrast, Lee reports the 12-month follow-up of the high-risk group from the UKUnited Kingdom National Health Service Bowel Cancer Screening Programme, where the risk of MANMetachronous advanced neoplasia was lower, at 6.6%. The European guidelines incorporate ≥5 adenomas and size ≥20mm in the highest risk group, giving no special consideration to the ≥10 adenomas group. More than 10 adenomas are recognised in the AGAAmerican Gastroenterological Association guidelines and Canadian Association of Gastroenterology guidelines as requiring surveillance at 1-year recommendation.
The Norwegian guidelines recommend surveillance at 10 years for patients with 1–2 adenomas, despite the presence of HGDHigh grade dysplasia or villous features or size ≥10mm.
A recent study based on long-term data from the Norwegian registry reported SMRStandardised mortality ratio for 40826 patients who had had adenomas removed. For, the high-risk group, CRCColorectal cancer-specific SMRStandardised mortality ratio was 1.16 (1.02-1.31) implying a surveillance interval of 10 years was adequate to reduce the SMRStandardised mortality ratio to just above average population risk, but inadequate to reduce it to or below average population risk.
In the Dutch surveillance programme, based on the personalised risk score developed by van Heijningen et al a surveillance interval of 3 years is recommended for those with a score of 3–5, while a surveillance interval of 5 years is recommended for those with a risk score of 1–2.
Evidence summary and recommendations
|The nine cohort studies of high-risk patients in whom surveillance was performed at 3–5 years reported an incidence of metachronous CRCColorectal cancer of 0.00% to 1.52%.||II, III-2||, , , , , , , , |
|Surveillance time primarily ranged between 3 and 5 years amongst the seven cohort studies that reported incidence of any adenoma in patients with high-risk adenomas. Adenoma incidence ranged from 36.63% to 69.71% across the seven studies.||II, III-2||, , , , , , |
|IncidenceAn epidemiological term reporting number of new cases in a population within a specified period. of metachronous advanced adenoma was not consistent among the 10 cohort studies and ranged from 2.40% to 24.24%. Surveillance time varied across these studies, with five studies reporting surveillance within 3 years, and seven studies reporting surveillance within 3–5 years.||II, III-2||, , , , , , , , , |
|Evidence-based recommendationA recommendation formulated after a systematic review of the evidence, indicating supporting references.||Grade|
High-risk individuals – conventional adenomas only
First surveillance intervals should be within 5 years following removal of high-risk conventional adenomas only, i.e. those with one or more of the following features:
|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.|
High-risk individuals – conventional adenomas only
First surveillance intervals following removal of high-risk conventional adenomas only should be stratified according to the type and number of high-risk features (size ≥10mm, high-grade dysplasia (HGDHigh grade dysplasia), villosity, 3–4 adenomas):
A surveillance interval of 5 years is recommended for patients with either of the following:
A surveillance interval of 3 years is recommended for patients with any of the following:
|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.|
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.|
Consistently high-quality colonoscopy is imperative for optimal cost effectiveness and for implementation of uniform surveillance guidelines.
|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.|
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).
Polyps removed at colonoscopy should be sent separately for histology to guide surveillance recommendations.
Clinicians should accurately include features relevant to surveillance intervals in their procedure reports so that individualised surveillance recommendations can be made.
Notes on the recommendations
The systematic review supported surveillance within 5 years following removal of high-risk conventional adenomas but did not offer guidance on intervals within this broad timeframe. General review of the literature assessed high-risk features and suggested that combinations of these features might guide further stratification relevant to clinical practice.
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.
The consensus-based recommendations are supported by the following key findings in the literature:
- Following removal of high-risk conventional adenomas, individuals require surveillance to reduce CRCColorectal cancer incidence and CRCColorectal cancer-specific mortality to levels at or just above population level.
- Whilst combinations of high-risk features are associated with an increased risk of metachronous neoplasia, subgroups of high-risk individuals seem to be at lesser risk. These lesser risk sub-groups include:
(i) those in whom 3–4 small tubular adenomas without HGDHigh grade dysplasia have been removed, and
(ii) those in whom 1–2 tubular adenomas without HGDHigh grade dysplasia have been removed, one of which is ≥10mm.
The recommendation for a 5-year surveillance interval following the removal of 3–4 low-risk adenomas without HGDHigh grade dysplasia is consistent with this recognition and attempts to counteract the 'paradoxical' impact that high quality colonoscopy (with detection of multiple small adenomas) would otherwise have on the number of and intervals between surveillance procedures. It represents a reduction in frequency, compared with the 2011 Australian clinical practice guidelines for surveillance colonoscopy.
Expert opinion and guidelines from other countries vary in their definitions of the high-risk group, with a trend towards separating off an intermediate risk group from those at highest risk (Table 4 Summary of international surveillance guidelines). Associated with this, there is variability in the corresponding surveillance interval recommendations. For the highest-risk group (albeit variably defined), a shorter surveillance interval of 1 year is recommended. Otherwise, a 3-year interval is recommended.
The British guidelines differ in that they make surveillance recommendations based on size and number alone.
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 do not currently 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.
ColorectalReferring to the large bowel, comprising the colon and rectum. cancer incidence and mortality after adenoma removal
Table 5. ColorectalReferring to the large bowel, comprising the colon and rectum. cancer incidence and mortality after adenoma removal
|Up to 10 years||Adjusted OR for CRCColorectal cancer incidence at follow-up after polypectomy:
<3 years: 0.2 (0.2–0.3), 3–5 years: 0.4 (0.3–0.6)
6–10 years: 0.9 (0.5–1.5) for low- and high-risk adenomas
cohort and registry
SIRStandardised incidence ratio 0.68 (0.44-0.99) regardless of follow-up;
SIRStandardised incidence ratio 0.60 (0.30-1.07) with a single follow-up colonoscopy
10-year cumulative probability of CRCColorectal cancer was 0.76% (0.39–1.48) with and 1.37% (0.70–2.65) without surveillance colonoscopy.
SIRStandardised incidence ratio 2.23 (1.67–2.92): 1.10 (0.62–1.82) with follow-up 4.26 (2.89–6.04) without;
10-year cumulative probability 2.05% (1.14–3.64) with 6.22% (4.26–9.02) without surveillance colonoscopy
|Atkin 2017||UKUnited Kingdom
Retrospective cohort study
|Incident adenomas 1990–2010
Follow-up through 2014
|3–4 small adenomas or 1–2 adenomas, at least one of which is ≥10mm
After adjustment for baseline risk factors, CRCColorectal cancer incidence in the whole cohort was not significantly different from that of the general population (SIRStandardised incidence ratio 1.09, 95% CI 0.91–1.30); compared with no surveillance, one surveillance visit at median 2.9 years (IQR 1.3–3.4), was associated with a significant reduction in CRCColorectal cancer incidence rate (HR 0.57, 95% CI 0.40–0.80).
|Low-risk group (no surveillance colonoscopy)
SMRStandardised mortality ratio 0.75 (0.63–0.88)
|High-risk group (surveillance colonoscopy every 10 years)
SMRStandardised mortality ratio 1.16 (1.02–1.31)
|Removal of the first adenoma
1993–1999: SMRStandardised mortality ratio 1.17 (1.03–1.33) vs. 2000–2007: 0.76 (0.65–0.89)
|Zauber 2012||USAUnited States of America
(NPSNational Polyp Study)
|SMRStandardised mortality ratio 0.47 (0.26–0.80) cumulative mortality at 20 years 0.8 vs. 1.5% in general population. The risk of CRCColorectal cancer mortality of those with adenomas removed was the same as those without adenomas at 10 years.|
|Abbreviations: CI: Confidence interval; CRCColorectal cancer: colorectal cancer; HR: hazard ratio; IQR: interquartile range; OR: odds ratio; SIRStandardised incidence ratio: standardised incidence ratio; SMRStandardised mortality ratio: standardised mortality ratio; UKUnited Kingdom: United Kingdom; USAUnited States of America: United States of America|
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|PICO question SAD 1||Evidence statement form SAD2||Systematic review report SAD2|