Risk of Metachronous Advanced Neoplasia in Patients With Multiple Diminutive Adenomas

Colon Polyp Surveillance: Separating the Wheat From the Chaff

One goal of colorectal cancer (CRC) screening is to prevent CRC incidence by removing precancerous colonic polyps, which are detected in up to 50% of screening examinations. Yet, the lifetime risk of CRC is 3.9%-4.3%, so it is clear that most of these individuals with polyps would not develop CRC in their lifetime. It is, therefore, a challenge to determine which individuals with polyps will benefit from follow-up, and at what intervals. There is some evidence that individuals with advanced polyps, based on size and histology, benefit from intensive surveillance. However, a large proportion of individuals will have small polyps without advanced histologic features (ie, "nonadvanced"), where the benefits of surveillance are uncertain and controversial. Demand for surveillance will further increase as more polyps are detected due to increased screening uptake, recent United States recommendations to expand screening to younger individuals, and emergence of polyp detection technology. We review the current understanding and clinical implications of the natural history, biology, and outcomes associated with various categories of colon polyps based on size, histology, and number. Our aims are to highlight key knowledge gaps, specifically focusing on certain categories of polyps that may not be associated with future CRC risk, and to provide insights to inform research priorities and potential management strategies. Optimization of CRC prevention programs based on updated knowledge about the future risks associated with various colon polyps is essential to ensure cost-effective screening and surveillance, wise use of resources, and inform efforts to personalize recommendations.

Artificial intelligence for colorectal neoplasia detection during colonoscopy: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

The use of artificial intelligence (AI) in detecting colorectal neoplasia during colonoscopy holds the potential to enhance adenoma detection rates (ADRs) and reduce adenoma miss rates (AMRs). However, varied outcomes have been observed across studies. Thus, this study aimed to evaluate the potential advantages and disadvantages of employing AI-aided systems during colonoscopy.

METHODS

Using Medical Subject Headings (MeSH) terms and keywords, a comprehensive electronic literature search was performed of the Embase, Medline, and the Cochrane Library databases from the inception of each database until October 04, 2023, in order to identify randomized controlled trials (RCTs) comparing AI-assisted with standard colonoscopy for detecting colorectal neoplasia. Primary outcomes included AMR, ADR, and adenomas detected per colonoscopy (APC). Secondary outcomes comprised the poly missed detection rate (PMR), poly detection rate (PDR), and poly detected per colonoscopy (PPC). We utilized random-effects meta-analyses with Hartung-Knapp adjustment to consolidate results. The prediction interval (PI) and I2 statistics were utilized to quantify between-study heterogeneity. Moreover, meta-regression and subgroup analyses were performed to investigate the potential sources of heterogeneity. This systematic review and meta-analysis is registered with PROSPERO (CRD42023428658).

FINDINGS

This study encompassed 33 trials involving 27,404 patients. Those undergoing AI-aided colonoscopy experienced a significant decrease in PMR (RR, 0.475; 95% CI, 0.294-0.768; I2 = 87.49%) and AMR (RR, 0.495; 95% CI, 0.390-0.627; I2 = 48.76%). Additionally, a significant increase in PDR (RR, 1.238; 95% CI, 1.158-1.323; I2 = 81.67%) and ADR (RR, 1.242; 95% CI, 1.159-1.332; I2 = 78.87%), along with a significant increase in the rates of PPC (IRR, 1.388; 95% CI, 1.270-1.517; I2 = 91.99%) and APC (IRR, 1.390; 95% CI, 1.277-1.513; I2 = 86.24%), was observed. This resulted in 0.271 more PPCs (95% CI, 0.144-0.259; I2 = 65.61%) and 0.202 more APCs (95% CI, 0.144-0.259; I2 = 68.15%).

INTERPRETATION

AI-aided colonoscopy significantly enhanced the detection of colorectal neoplasia detection, likely by reducing the miss rate. However, future studies should focus on evaluating the cost-effectiveness and long-term benefits of AI-aided colonoscopy in reducing cancer incidence.

FUNDING

This work was supported by the Heilongjiang Provincial Natural Science Foundation of China (LH2023H096), the Postdoctoral research project in Heilongjiang Province (LBH-Z22210), the National Natural Science Foundation of China's General Program (82072640) and the Outstanding Youth Project of Heilongjiang Natural Science Foundation (YQ2021H023).

Risk Factors for Metachronous Colorectal Cancer or Advanced Adenomas After Endoscopic Resection of High-risk Adenomas

BACKGROUND & AIMS

Among the characteristics of high-risk adenomas (HRAs), some may predict a higher risk of metachronous advanced lesions. Our aim was to assess which HRA characteristics are associated with high risk of metachronous colorectal cancer (CRC) or advanced adenomas (AAs).

METHODS

We systematically searched Pubmed, EMBASE, and Cochrane for cohort studies and clinical trials of CRC or AA incidence at surveillance stratified by baseline lesion size, histology, and multiplicity. We calculated pooled relative risks (RRs) using a random-effects model. Heterogeneity was assessed with the I² statistic.

RESULTS

Fifty-five studies were included, with 936,540 patients with mean follow-up 5.4 ± 2.9 years. CRC incidence per 1000 person-years was 2.6 (2.1-3.0) for adenomas ≥20 mm, 2.7 (2.2-3.2) for high-grade dysplasia (HGD), 2.0 (1.8-2.3) for villous component, 0.8 (0.1-1.4) for ≥5 adenomas, 1.0 (0.7-1.2) for ≥3 adenomas. Metachronous CRC risk was higher in adenomas ≥20 mm vs 10 to 19 mm (RR, 2.08; 95% confidence interval [CI], 1.20-3.61), HGD vs low-grade dysplasia (RR, 2.89; 95% CI, 1.88-4.44), villous vs tubular (RR, 1.75; 95% CI, 1.33-2.31). No significant differences in CRC risk were found in ≥3 adenomas vs 1 to 2 (RR, 1.24; 95% CI, 0.84-1.83), nor in ≥5 adenomas vs 3 to 4 (RR, 0.79; 95% CI, 0.30-2.11). Compared with normal colonoscopy, RR for CRC risk was 2.61 (95% CI, 2.06-3.32) for ≥10mm, 6.62 (95% CI, 4.60-9.52) for HGD, 3.58 (95% CI, 2.24-5.73) for villous component, and 2.03 (95% CI, 1.40-2.94) for ≥3 adenomas. Similar trends were seen for metachronous AAs.

CONCLUSION

Metachronous CRC risk is highest in patients with baseline adenomas with ≥20 mm or HGD. Multiplicity does not seem to be associated with substantially higher CRC risk in the near term.

Clinical outcomes of colonoscopic polypectomy with strategic surveillance colonoscopies in patients with 10 or more polyps

The clinical usefulness of repeat colonoscopic polypectomy in patients with numerous polyps has not been sufficiently determined. We aimed to analyze the clinical outcomes of colonoscopic polypectomy with surveillance colonoscopies in patients with ≥ 10 polyps. We reviewed the medical records of 152 patients who underwent polypectomy of ≥ 10 polyps at the baseline colonoscopy. We investigated polyp number, polyp size, polypectomy method, procedure time, and adverse events of the baseline colonoscopy. We also investigated the frequency and interval of surveillance colonoscopies and their findings. The mean number of polyps detected at the baseline colonoscopy was 20.0, of which 16.0 polyps were endoscopically resected. The mean size of the largest polyp was 13.4 mm. The mean procedure time was 54.9 min. Post-polypectomy bleeding occurred in 6 (3.9%) patients, all of whom were treated conservatively. No patients developed perforation. With an increasing number of surveillance colonoscopies, the number of detected polyps and the procedure time decreased. Surveillance colonoscopies identified colorectal cancer only in three patients (2.0%), all of which were mucosal cancers that could be curatively treated by polypectomy. Colonoscopic polypectomy with repeat surveillance colonoscopies is a clinically effective, efficient, and safe management option in patients with ≥ 10 polyps.

Korean Guidelines for Postpolypectomy Colonoscopic Surveillance: 2022 revised edition

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for managing advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of the limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: adenoma ≥10 mm in size; 3 to 5 (or more) adenomas; tubulovillous or villous adenoma; adenoma containing high-grade dysplasia; traditional serrated adenoma; sessile serrated lesion containing any grade of dysplasia; serrated polyp of at least 10 mm in size; and 3 to 5 (or more) sessile serrated lesions. More studies are needed to fully comprehend the patients who are most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Risk of Metachronous Advanced Colorectal Neoplasia After Removal of Diminutive Versus Small Nonadvanced Adenomas: A Multicenter Study

BACKGROUND

Current postpolypectomy guidelines treat 1-9 mm nonadvanced adenomas (NAAs) as carrying the same level of risk for metachronous advanced colorectal neoplasia (ACRN).

AIMS

To evaluate whether small (6-9 mm) NAAs are associated with a greater risk of metachronous ACRN than diminutive (1-5 mm) NAAs.

METHODS

We retrospectively evaluated 10,060 index colonoscopies performed from July 2011 to June 2019. A total of 1369 patients aged ≥ 40 years with index NAAs and having follow-up examinations were categorized into 5 groups based on size and number of index findings: Group 1, ≤ 2 diminutive NAAs (n = 655); Group 2, ≤ 2 small NAAs (n = 529); Group 3, 3-4 diminutive NAAs (n = 78); Group 4, 3-4 small NAAs (n = 65); and Group 5, 5-10 NAAs (n = 42). Size was classified based on the largest NAA. ACRN was defined as finding an advanced adenoma or colorectal cancer at follow-up.

RESULTS

The absolute risk of metachronous ACRN increased from 7.2% in patients with all diminutive NAAs to 12.2% in patients with at least 1 small NAA (P = 0.002). Patients in Group 2 (adjusted odds ratio [AOR] 1.89; 95% confidence interval [CI], 1.21-2.95), Group 3 (AOR 2.40; 95% CI 1.78-4.90), Group 4 (AOR 2.77; 95% CI 1.35-5.66), and Group 5 (AOR 3.71; 95% CI 1.65-8.37) were associated with an increased risk of metachronous ACRN compared with Group 1.

CONCLUSIONS

Patients with small NAAs have an increased risk of metachronous ACRN. Postpolypectomy guidelines should consider including risk stratification between small and diminutive adenomas.

Korean guidelines for postpolypectomy colonoscopic surveillance: 2022 revised edition

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for the management of advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: (1) adenoma ≥10 mm in size; (2) 3 to 5 (or more) adenomas; (3) tubulovillous or villous adenoma; (4) adenoma containing high-grade dysplasia; (5) traditional serrated adenoma; (6) sessile serrated lesion (SSL) containing any grade of dysplasia; (7) serrated polyp of at least 10 mm in size; and (8) 3 to 5 (or more) SSLs. More studies are needed to fully comprehend the patients most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Risk of adenoma recurrence after polypectomy in patients younger than 50 years vs. 50 years old and over with diminutive or small adenomas

Background and aims

Current studies have shown that polyp recurrence occurs after colonic adenomas polypectomy (AP), but the difference in recurrence risk between patients in patients older than 50 years and younger than 50 years has not been clearly studied.

Methods

490 patients after AP were enrolled in the study. The patients were classified according to age (<50 years old or ≥50 years old), and then further categorized according to the baseline adenoma characteristics: Group 1: 1–2 non-advanced adenomas (NAAs) 1–5 mm in size; Group 2: ≥3 NAAs, 1–5 mm; Group 3: 1–2 NAAs, 6–9 mm; Group 4: ≥3 NAAs, 6–9 mm; and Group 5: advanced adenomas.

Results

During a mean follow-up interval of 2.52 years (2.51 years for ≥50 years old and 2.55 years for patients <50 years old), NAA recurrence was detected in 147 patients (30.0%). Overall, the hazard ratio (HR) for NAA recurrence after AP was higher in patients ≥50 years old than that in patients <50 years old (HR, 1.774, P = 0.003). For patients <50 years old, HRs (Group 2-5 vs. G1, respectively) for NAA recurrence were 0.744 (P = 0.773), 3.885 (P = 0.007), 5.337 (P = 0.003), and 3.334 (P = 0.015). For patients ≥50 years old, HRs (Group 2-5 vs. G1, respectively) for NAA recurrence were 1.033 (P = 0.965), 1.250 (P = 0.405), 2.252 (P = 0.015), and 1.887 (P = 0.009). For G1, the risk of NAA recurrence was significantly higher in patients ≥50 years old (HR, 2.932, P = 0.011) than that in patients <50 years old; for G2–G5, the risk was similar in the two age groups (P > 0.05).

Conclusions

For patients <50 years old with less than 3 NAAs that are 1–5 mm in size, the recurrence rate of NAA is less than that of patients ≥50 years old with the same index colonoscopy findings. When the adenomas are ≥5 mm, or their number exceeds 3, they have similar recurrence risk as that for patients ≥50 years old.

[Korean Guidelines for Postpolypectomy Colonoscopic Surveillance: 2022 Revised Edition]

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for managing advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of the limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: 1) adenoma ≥10 mm in size; 2) 3-5 (or more) adenomas; 3) tubulovillous or villous adenoma; 4) adenoma containing high-grade dysplasia; 5) traditional serrated adenoma; 6) sessile serrated lesion (SSL) containing any grade of dysplasia; 7) serrated polyp of at least 10 mm in size; and 8) 3-5 (or more) SSLs. More studies are needed to fully comprehend the patients who are most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Does computer-aided diagnostic endoscopy improve the detection of commonly missed polyps? A meta-analysis

Background/Aims

Colonoscopy is the gold standard diagnostic method for colorectal neoplasia, allowing detection and resection of adenomatous polyps; however, significant proportions of adenomas are missed. Computer-aided detection (CADe) systems in endoscopy are currently available to help identify lesions. Diminutive (≤5 mm) and nonpedunculated polyps are most commonly missed. This meta-analysis aimed to assess whether CADe systems can improve the real-time detection of these commonly missed lesions.

Methods

A comprehensive literature search was performed. Randomized controlled trials evaluating CADe systems categorized by morphology and lesion size were included. The mean number of polyps and adenomas per patient was derived. Independent proportions and their differences were calculated using DerSimonian and Laird random-effects modeling.

Results

Seven studies, including 2,595 CADe-assisted colonoscopies and 2,622 conventional colonoscopies, were analyzed. CADe-assisted colonoscopy demonstrated an 80% increase in the mean number of diminutive adenomas detected per patient compared with conventional colonoscopy (0.31 vs. 0.17; effect size, 0.13; 95% confidence interval [CI], 0.09–0.18); it also demonstrated a 91.7% increase in the mean number of nonpedunculated adenomas detected per patient (0.32 vs. 0.19; effect size, 0.05; 95% CI, 0.02–0.07).

Conclusions

CADe-assisted endoscopy significantly improved the detection of most commonly missed adenomas. Although this method is a potentially exciting technology, limitations still apply to current data, prompting the need for further real-time studies.

Risk of Metachronous Colorectal Advanced Neoplasia and Cancer in Patients With 3-4 Nonadvanced Adenomas at Index Colonoscopy: A Systematic Review and Meta-Analysis

INTRODUCTION

This systematic review and meta-analysis evaluated the available evidence on the risk of metachronous advanced neoplasia (AN) and colorectal cancer (CRC) in patients with 3-4 nonadvanced adenomas (NAAs).

METHODS

We searched MEDLINE, EMBASE, and Cochrane Library databases up to January 2021 for studies evaluating metachronous AN and CRC risk by comparing 3 groups (1-2 vs 3-4 vs ≥5 NAAs) at index colonoscopy. The estimates for risk of metachronous AN and CRC were evaluated using random-effects models.

RESULTS

Fifteen studies (n = 36,375) were included. The risk of metachronous AN was significantly higher in the 3-4 NAAs group than in the 1-2 NAAs group (relative risk [RR] 1.264, 95% confidence interval [CI] 1.053-1.518, P = 0.012; I2 = 0%); there was no difference between the ≥ 5 NAAs and 3-4 NAAs groups (RR 1.962, 95% CI 0.972-3.958, P = 0.060; I2 = 68%). The risks of metachronous CRC between the 1-2 NAAs and 3-4 NAAs groups (RR 2.663, 95% CI 0.391-18.128, P = 0.317; I2 = 0%) or the 3-4 NAAs and ≥ 5 NAAs groups (RR 1.148, 95% CI 0.142-9.290, P = 0.897; I2 = 0%) were not significantly different.

DISCUSSION

Although the risk of metachronous AN was greater in the 3-4 NAAs group than in the 1-2 NAAs group, the risk of metachronous AN and CRC between the 3-4 NAAs and ≥ 5 NAAs groups was not different. This suggests that further studies on metachronous AN and CRC risk in the 3-4 NAAs group are warranted to confirm a firm ≥5-year interval surveillance colonoscopy.

Surveillance Recommendation for Colonoscopy after Polypectomy

The incidence and mortality of colorectal cancer (CRC) have declined over the past several decades, largely due to improvement and uptake in screening, particularly with colonoscopy. The US Multi-Society Task Force on CRC published guidelines for surveillance after polypectomy in 2012, which were updated in 2020 with some important changes, and this review will provide an updated overview of evidence and outcomes of surveillance after polypectomy. Notable modifications to surveillance guidelines include increasing interval time between colonoscopies from 5 to 7 to 10 years for 1 to 2 low-risk adenomas (<10 mm) and from 3 years to 3 to 5 years when 3 to 4 low-risk adenomas are identified.

Yield and Risk Factors for Advanced Colorectal Neoplasia and Long-term Outcomes in Veterans With 3 or More Nonadvanced Adenomas

BACKGROUND AND AIMS

Until recently, guidelines recommended a 3-year surveillance colonoscopy for persons with 3 to 10 nonadvanced adenomas (NAA). In this study, we quantify yield for metachronous advanced neoplasia (AN); attempt to identify risk factors for AN; and measure colorectal cancer (CRC) incidence and mortality.

METHODS

We used natural language processing to screen an existing data set for Veterans with 3 to 10 NAA. We manually reviewed colonoscopy and pathology reports to verify baseline findings and determine results of subsequent colonoscopy (sCY). Baseline features were extracted from the electronic medical record (EMR) and a national data set, CRC incidence was obtained from the Veterans Affairs cancer registry, and CRC mortality from the National Death Index through September 30, 2017. CRC incidence and mortality were compared between Veterans who did versus did not have sCY.

RESULTS

Natural language processing identified 3673 Veterans who potentially had 3 to 10 NAA, of which 1672 were excluded after EMR review. In the analytical cohort of 2001 subjects, 1178 (59%) had sCY at a mean (SD) follow-up of 4.3 (2.2) years. The sCY group was younger (mean age: 61 vs. 67 y; P<0.01) and were less likely to have diabetes (27% vs. 31%; P=0.02) and congestive heart failure (4% vs. 9%; P<0.01). sCY showed AN in 182 subjects (15.5%). Baseline features were no different between those with versus without metachronous AN. Subjects with sCY had a greater CRC incidence (n=7 vs. n=0; P=0.046), but there was no difference in CRC mortality (0 for both subgroups).

CONCLUSIONS

Among patients with 3 to 10 NAA on index colonoscopy who underwent sCY, AN was present in 15.5% at mean follow-up of 4.3 years. No risk factors for AN were identified. CRC incidence, but not CRC mortality, was higher among those with sCY.

Early-Onset Colorectal Cancer Is Associated with a Lower Risk of Metachronous Advanced Neoplasia than Traditional-Onset Colorectal Cancer

BACKGROUND

Colorectal cancer (CRC) incidence in the USA has increased in adults under age 50. Current CRC surveillance guidelines do not consider age at diagnosis, and there are limited data available on outcomes from surveillance colonoscopies in early-onset CRC (EO-CRC) to guide recommendations on surveillance intervals.

AIMS

To compare surveillance outcomes between EO-CRC and traditional-onset colorectal cancer (TO-CRC).

METHODS

In a retrospective cohort study in a large tertiary care academic medical center, we collected data on patients with a diagnosis of CRC between 2000 and 2014 who received surgery with curative intent. We used log-rank test and inverse probability of treatment weighted Cox regression analysis to compare the development of metachronous advanced neoplasia (MAN) in patients with EO-CRC (diagnosed ages 18-49) and TO-CRC (diagnosed ages 50-75).

RESULTS

Patients with EO-CRC (n = 107) were more likely to present with advanced-stage disease (62% versus 35%, p < 0.0001), rectal tumors (45% versus 27%, p < 0.01), and a family history of CRC (30% versus 16%, p = 0.02) compared to those with TO-CRC (n = 139). Patients with EO-CRC had lower risk of MAN (adjusted HR 0.44, 95% CI 0.22-0.88) than TO-CRC patients. The 5-year event rate for MAN was lower for patients with EO-CRC compared to patients with TO-CRC (5.8% vs. 16.1%, p = 0.07). The presence of synchronous neoplasia or history of diabetes was also predictive of MAN.

CONCLUSIONS

EO-CRC was independently associated with a lower risk of developing MAN compared to TO-CRC. Shorter surveillance intervals may not be warranted in EO-CRC; however, large prospective studies are needed.

Prevalence of Metachronous Advanced Colorectal Neoplasia in Black and White Patients at a Safety Net Hospital

Background and Aims

Current postpolypectomy surveillance guidelines are based primarily on data from non-Hispanic Whites (NHWs); thus, generalizability to non-Hispanic Blacks (NHBs) remains unknown. Hence, the primary objective of this study was to assess the validity of these guidelines for NHBs by comparing the prevalence of metachronous advanced colorectal neoplasia (ACN) between NHWs and NHBs undergoing surveillance colonoscopy.

Methods

This was a retrospective cross-sectional study of NHWs (N = 1500) and NHBs (N = 1260) aged 40-75 years who underwent surveillance colonoscopy at an academic safety net hospital between 2007 and 2017. The primary outcome measure was the prevalence of metachronous ACN, defined as an advanced adenoma, advanced sessile polyp, or invasive cancer. Multivariate logistic regression was used to measure associations between race/ethnicity and ACN prevalence after adjustment for potential confounding factors.

Results

Overall, the prevalence of metachronous ACN was similar for NHBs and NHWs (6.8% vs 7.4%, respectively; P = .60). The prevalence of metachronous cancers (0.2% vs 0.1%; P = .48), advanced adenomas (2.8% vs 3.8%; P = .14), advanced serrated polyps (3.5% vs 3.3%; P = .82), and large hyperplastic polyps ≥10 mm (0.2% vs 0.6%, P = .24) were also similar between the 2 groups. Moreover, race was not a determinant of metachronous ACN after adjustment for age, sex, education, type of insurance, indication (screen/surveillance) for baseline colonoscopy, surveillance interval, and findings at baseline colonoscopy (adjusted odds ratio, 0.96; 95% confidence interval, 0.70-1.30; P = .78).

Conclusion

Our study finds no significant difference in the prevalence of metachronous ACN between NHWs and NHBs undergoing appropriate postpolypectomy surveillance at an urban safety net hospital, suggesting that current guidelines are appropriate for both NHWs and NHBs.

Higher Adenoma Detection Rates at Screening Associated With Lower Long-Term Colorectal Cancer Incidence and Mortality

BACKGROUND & AIMS

Detection and removal of adenomas reduces colorectal cancer (CRC) risk. The impact of adenoma detection rates (ADRs) on long-term CRC incidence and mortality is unknown. We investigated this using data from the UK Flexible Sigmoidoscopy Screening Trial.

METHODS

Of 167,882 UK Flexible Sigmoidoscopy Screening Trial participants, 40,085 were in the intervention arm and underwent flexible sigmoidoscopy screening at 13 trial centers. The median follow-up time was 17 years. At each center, 1 endoscopist performed most flexible sigmoidoscopies. Multivariable logistic regression was used to classify centers into high-, intermediate-, and low-detector groups based on their main endoscopist's ADR. We calculated the incidence and mortality of distal and all-site CRC, and estimated hazard ratios (HRs) with 95% CIs using Cox regression.

RESULTS

Five, 4, and 4 centers, respectively, were classified into the high-detector, intermediate-detector, and low-detector groups. The average ADRs in each respective group were 15%, 12%, and 9%. Distal CRC incidence and mortality were reduced among those screened compared with controls in all groups, and effects of screening varied significantly by detector ranking, with larger reductions in incidence and mortality seen in the high-detector group (incidence: HR, 0.34; 95% CI, 0.27-0.42; mortality: HR, 0.22, 95% CI, 0.13-0.37) than in the low-detector group (incidence: HR, 0.55; 95% CI, 0.44-0.68; mortality: HR, 0.54; 95% CI, 0.34-0.86). Similar results were observed for all-site CRC, with larger effects seen in the high-detector (incidence: HR, 0.58; 95% CI, 0.50-0.67; mortality: HR, 0.52; 95% CI, 0.39-0.69) than in the low-detector group (incidence: HR, 0.72; 95% CI, 0.61-0.85; mortality: HR, 0.68; 95% CI, 0.51-0.92), although the heterogeneity was not statistically significant.

CONCLUSIONS

Higher ADRs at screening provide greater long-term protection against CRC incidence and mortality. Isrctn.org, number: ISRCTN28352761.

Helicobacter pylori Infection and the Development of Advanced Colorectal Neoplasia

BACKGROUND

An association between Helicobacter pylori infection and colorectal neoplasia has been reported in cross-sectional studies.

GOALS

We examined the association between H. pylori infection and the development of advanced colorectal neoplasia (AN) in a screening cohort.

STUDY

We identified 3753 adults, who underwent screening and subsequent surveillance colonoscopies. The primary outcome was the development of metachronous AN, as confirmed by surveillance colonoscopy. H. pylori infection status was assessed by an H. pylori-specific immunoglobulin G antibody test. Sensitivity analysis was also performed by H. pylori infection status on the basis of histology.

RESULTS

During a median follow-up of 41 months, the incidence of AN was 3.2% and 1.7% in participants with and without H. pylori infection, respectively. In multivariable analysis adjusted for age, body mass index, smoking status, alcohol intake, family history of colorectal cancer, and baseline adenoma characteristics, the hazard ratio [95% confidence interval (CI)] for metachronous AN was 1.74 (1.11-2.73) in participants with H. pylori seropositivity, compared with those without H. pylori seropositivity. The association was consistent with H. pylori infection status on the basis of histology (adjusted hazard ratio, 3.51; 95% CI, 1.64-7.51). In the subgroup analysis, the positive association was observed in both no-adenoma and adenoma removal subgroups.

CONCLUSIONS

In a cohort study, H. pylori infection was associated with an increased risk of AN development. This association was consistent in both the serological and histologic assessment of H. pylori infection. Prospective studies are necessary to determine whether H. pylori eradication can reduce the risk of colorectal neoplasia.

Comparative systematic review and meta-analysis of 1- to 5-mm versus 6- to 9-mm adenomas on the risk of metachronous advanced colorectal neoplasia

BACKGROUND AND AIMS

The current guidelines recommend the same surveillance interval for ≥3 nonadvanced adenomas (NAAs), without discriminating between diminutive (1-5 mm) and small (6-9 mm) adenomas. Additionally, the same surveillance interval is recommended for patients with ≤2 diminutive NAAs and those with ≤2 small NAAs. However, it is questionable whether these recommendations are appropriate.

METHODS

We searched all relevant studies published through September 2019 that examined the risk of metachronous advanced colorectal neoplasia (ACRN) according to the size (diminutive vs small) and the number of adenomas found during an index colonoscopy. Low-risk adenomas (LRAs) were subclassified into 2 categories (LRA-1, ≤2 diminutive NAAs; and LRA-2, ≤2 small NAAs), and high-risk adenomas (HRAs) were subclassified into 3 categories (HRA-1, ≥3 diminutive NAAs; HRA-2, ≥3 small NAAs; and HRA-3, advanced adenoma).

RESULTS

Eight studies involving 36,142 patients were evaluated. The LRA-2 group had a higher risk of metachronous ACRN than the LRA-1 group (risk ratio, 1.49; 95% confidence interval [CI], 1.23-1.81). Additionally, the HRA-2 and HRA-3 groups had a higher risk of metachronous ACRN than the HRA-1 group (hazard ratios [HRs], 1.51 [95% CI, 1.002-2.28] and 1.92 [95% CI, 1.11-3.33], respectively). However, there was no significant difference between the HRA-1 versus LRA-2 groups (HR, 1.23; 95% CI, .78-1.94).

CONCLUSIONS

Among the HRA and LRA groups, those with diminutive NAAs had a lower risk of metachronous ACRN than those with small NAAs. We believe that clinical guidelines should consider extending the surveillance intervals in patients with diminutive NAAs only.

Baseline Colonoscopy Findings Associated With 10-Year Outcomes in a Screening Cohort Undergoing Colonoscopy Surveillance

BACKGROUND & AIMS

Few studies have evaluated long-term outcomes of ongoing colonoscopic screening and surveillance in a screening population. We aimed to determine the 10-year risk for advanced neoplasia (defined as adenomas ≥10mm, adenomas with villous histology or high-grade dysplasia, or colorectal cancer [CRC]) and assessed whether baseline colonoscopy findings were associated with long-term outcomes.

METHODS

We collected data from the Department of Veterans Affairs Cooperative Studies Program Study on 3121 asymptomatic veterans (50-75 years old) who underwent a screening colonoscopy from 1994 through 1997 at 13 medical centers and were then followed for 10 years or until death. We included 1915 subjects with at least 1 surveillance colonoscopy and estimated cumulative incidence of advanced neoplasia by Kaplan-Meier curves. We then fit a longitudinal joint model to estimate risk of advanced neoplasia at each subsequent examination after baseline, adjusting for multiple colonoscopies within individuals.

RESULTS

Through 10 years of follow-up, there were 146 individuals among all baseline colonoscopy groups found to have at least 1 incident advanced neoplasia. The cumulative 10-year incidence of advanced neoplasia was highest among those with baseline CRC (43.7%; 95% CI 13.0%-74.4%), followed by those with baseline advanced adenoma (AA) (21.9%; 95% CI 15.7-28.1). The cumulative 10-year incidence of advanced neoplasia was 6.3% (95% CI 4.1%-8.5%) and 4.1% (95% CI 2.7%-5.4%) for baseline 1 to 2 small adenomas (<1cm, and without villous histology or high-grade dysplasia) and no neoplasia, respectively (log-rank P = .10). After adjusting for prior surveillance, the risk of advanced neoplasia at each subsequent examination was not significantly increased in veterans with 1 or 2 small adenomas at baseline (odds ratio 0.96; 95% CI 0.67-1.41) compared with veterans with no baseline neoplasia.

CONCLUSIONS

Baseline screening colonoscopy findings associate with advanced neoplasia within 10 years. Individuals with only 1 or 2 small adenomas at baseline have a low risk of advanced neoplasia over 10 years. Alternative surveillance strategies, could be considered for these individuals.

Risk of developing metachronous advanced colorectal neoplasia after resection of low-risk diminutive versus small adenomas

BACKGROUND AND AIMS

Current postpolypectomy guidelines classify 1 to 2 diminutive (1-5 mm) nonadvanced adenomas (NAAs) and 1 to 2 small (6-9 mm) NAAs as low-risk adenomas and recommend the same surveillance interval for both lesions. We compared the risk of metachronous advanced colorectal neoplasia (ACRN) for both groups.

METHODS

We studied 8602 patients who underwent removal of ≥1 NAA and follow-up colonoscopic surveillance. Patients were categorized into 4 groups based on size and number of baseline NAAs: group 1, ≤2 diminutive NAAs (n = 6379); group 2, ≤2 small NAAs (n = 1672); group 3, ≥3 diminutive NAAs (n = 293); and group 4, ≥3 small NAAs (n = 258). Size was classified based on the largest NAA.

RESULTS

The 5-year cumulative incidence rates of metachronous ACRN in groups 1, 2, 3, and 4 were 2.7%, 5.1%, 10.7%, and 15.1%, respectively. Groups 2, 3, and 4 had a higher risk of metachronous ACRN than group 1. Compared with group 1, the adjusted hazard ratios for metachronous ACRN were 2.06 (95% confidence interval [CI], 1.46-2.91) for group 2, 2.75 (95% CI, 1.53-4.96) for group 3, and 4.49 (95% CI, 2.62-7.70) for group 4. However, the risk of metachronous ACRN was not significantly different between groups 3 and 4 (adjusted hazard ratio, 1.62; 95% CI, .76-3.44).

CONCLUSIONS

Among patients with ≤2 NAAs, patients with 1- to 5-mm NAAs had a lower risk of metachronous ACRN than those with 6- to 9-mm NAAs. The guidelines should consider extending surveillance intervals in patients with ≤2 diminutive NAAs.

Does Colon Polyp Surveillance Improve Patient Outcomes?

Colon polyp surveillance now accounts for 25% of all colonoscopies performed. The evidence that colonoscopy surveillance reduces colorectal cancer (CRC) incidence or mortality is weak. The biology of the baseline lesions and quality of the baseline exam are two primary factors contributing to post-colonoscopy CRC. Prior recommendations for surveillance were based largely on the likelihood that patients with adenomas would develop advanced adenomas, a surrogate for CRC. There is now evidence that baseline colonoscopy findings are strongly associated with the risk of incidence or death from CRC. This evidence provides a basis for updated evidence-based recommendations for surveillance. In addition, there is also growing evidence that the quality of the baseline exam is an important predictor of the likelihood of developing post-colonoscopy CRC.

Risk of Developing Metachronous Advanced Colorectal Neoplasia After Polypectomy in Patients With Multiple Diminutive or Small Adenomas

INTRODUCTION

Current post-polypectomy guidelines recommend a 3-year surveillance interval for ≥3 nonadvanced adenomas (NAAs) without discrimination between diminutive (1-5 mm) and small (6-9 mm) adenomas. We compared the risk of metachronous advanced colorectal neoplasia (ACRN) among these groups.

METHODS

We studied 9,733 patients who underwent ≥1 adenoma removal and follow-up colonoscopic surveillance. Patients were classified based on baseline adenoma characteristics: group 1, 1-2 NAAs (n = 8,051); group 2, ≥3 diminutive NAAs (n = 293); group 3, ≥3 small NAAs (n = 258); and group 4, advanced adenomas (AAs) (n = 1,131).

RESULTS

The mean age of the study population was 45.8 ± 8.2 years. In group 4, most patients (94.5%) had 1 AA. The 3- and 5-year cumulative incidence rates of metachronous ACRN in groups 1, 2, 3, and 4 were 0.9%, 2.8%, 3.5%, and 4.0% and 3.1%, 10.7%, 15.1%, and 8.5%, respectively. Groups 2, 3, and 4 had a higher risk of metachronous ACRN than group 1. Compared with those for group 1, adjusted hazard ratios (95% confidence interval) for metachronous ACRN were 2.07 (1.16-3.68), 3.29 (1.94-5.56), and 2.73 (2.00-3.72) for groups 2, 3, and 4, respectively. However, this relationship was statistically insignificant between groups 2, 3, and 4. Compared with those for group 2, adjusted hazard ratios (95% confidence intervals) for groups 3 and 4 were 1.59 (0.76-3.30) and 1.32 (0.72-2.42), respectively, and 0.83 (0.47-1.46) for group 4 compared with group 3. The results of patients aged ≥50 years were identical to those of all patients.

DISCUSSION

Risk of metachronous ACRN was not different between patients aged ≥50 years who underwent polypectomy of ≥3 diminutive NAAs, ≥3 small NAAs, and AA, thus supporting current guidelines that recommend a uniform surveillance interval for these lesions.

Association of small versus diminutive adenomas and the risk for metachronous advanced adenomas: data from the New Hampshire Colonoscopy Registry

BACKGROUND AND AIMS

Limited data are available to investigate the impact of index adenoma size on the risk of metachronous advanced adenomas. Our goal was to examine the impact of having small (5-9 mm) versus diminutive (<5 mm) adenomas on the future risk of advanced adenomas within the categories for polyps <1 cm currently used in the United States: 1 to 2 and 3 or more tubular adenomas.

METHODS

We included data from individuals participating in the statewide, population-based New Hampshire Colonoscopy Registry (NHCR). Groups were based on index findings: (1) 1 to 2 adenomas <5 mm (both diminutive), (2) 1 to 2 adenomas <1 cm (one or both small), (3) 3 to 10 adenomas <5 mm (all diminutive), (4) 3 to 10 adenomas <1 cm (one or more small), and (5) advanced adenomas (AA). AAs were defined as adenomas ≥1cm or those with villous elements or high-grade dysplasia or colorectal cancer (CRC). Outcomes were the absolute and adjusted risk of metachronous AAs. Covariates included age, sex, body mass index, family history of CRC, lifestyle factors, presence of serrated polyps, and time since the index examination.

RESULTS

After adjusting for the covariates, we observed that having 1 to 2 adenomas with at least one 5 to 9 mm adenoma (adjusted odds ratio [AOR], 1.54; 95% confidence interval [CI], 1.12-2.11), 3 to 10 diminutive adenomas (AOR, 1.75; 95% CI, 1.03-2.95), 3 to 10 adenomas <1 cm (1 or more small) (AOR, 2.14; 95% CI, 1.39-3.29) or AAs (AOR, 2.77; 95% CI, 2.05-3.74) were associated with an increased risk for metachronous AA compared with having 1 to 2 diminutive adenomas. A further stratification of group 2 showed that those with exactly 2 small adenomas had an absolute risk of future AA of 7.6% (11/144) (95% CI, 4.3%-13.2%), higher than the absolute risk in the 1 to 2 diminutive polyp group, and similar to the risk for 3 to 10 adenomas of 8.2% (95% CI, 5.4-11.9).

CONCLUSIONS

For individuals with 1 to 2 adenomas <1 cm, having at least 1 small adenoma increased the metachronous risk of AA compared with having only diminutive adenomas. Furthermore, the subset with 2 small adenomas had a risk of future AA similar to the risk for 3 to 10 adenomas. These data suggest that individuals with at least 1 small adenoma may be at higher risk for future AAs and thus require closer follow-up than those with only diminutive adenomas. These data may be valuable to guideline committees for the creation of future surveillance recommendations.

Update in Surveillance Recommendations in Individuals With Conventional Adenomas

PURPOSE OF REVIEW

Conventional adenomas, which are precursors to almost 70% of colorectal carcinomas, are found in more than one-third of screening colonoscopies. Surveillance recommendations, based on adenoma size, histology, and number, have evolved over the years and are currently reflective of index adenoma categorization as either low-risk (LRA) or high-risk (HRA). In this review, recent guideline recommendations as well as primary data that have helped to shape these recommendations are presented.

RECENT FINDINGS

Recent data have demonstrated that individuals with HRA on index exams may be at increased risk for CRC while those with LRA may have a minimal long-term risk for CRC, similar to those adults with normal index exams. Furthermore, the quality of the index exams is important for minimizing CRC risk. While individuals with HRA may require close surveillance intervals of 3 years, those with LRA or normal exams may need longer such as 10-year follow-up.

Thinking Big About Small Adenomas: Moving Toward "Precision Surveillance"

Quality metrics and technological advances for colonoscopy are contributing to detection of more diminutive and small adenomas, increasing the proportion of persons undergoing surveillance for non-advanced neoplasia. In this issue, Kim and colleagues report surveillance colonoscopy findings in average-risk Koreans who had one or more adenomas on a first screening colonoscopy and found a similar risk of metachronous advanced neoplasia between those with 1-2 non-advanced adenoma (the "low-risk adenoma" group) and those with 3 or more small adenomas. The validity, generalizability, and clinical implications of the findings are considered along with recent similar studies. In sum, these studies support expanding the low-risk subgroup to include up to four diminutive tubular adenomas and perhaps persons with up to four small tubular adenomas. They also prompt consideration of "precision surveillance" that considers features of not just the polyps, but of the patient and endoscopist.