Considerations regarding the present and future roles of colonoscopy in colorectal cancer prevention

Microbiome confounders and quantitative profiling challenge predicted microbial targets in colorectal cancer development

Despite substantial progress in cancer microbiome research, recognized confounders and advances in absolute microbiome quantification remain underused; this raises concerns regarding potential spurious associations. Here we study the fecal microbiota of 589 patients at different colorectal cancer (CRC) stages and compare observations with up to 15 published studies (4,439 patients and controls total). Using quantitative microbiome profiling based on 16S ribosomal RNA amplicon sequencing, combined with rigorous confounder control, we identified transit time, fecal calprotectin (intestinal inflammation) and body mass index as primary microbial covariates, superseding variance explained by CRC diagnostic groups. Well-established microbiome CRC targets, such as Fusobacterium nucleatum, did not significantly associate with CRC diagnostic groups (healthy, adenoma and carcinoma) when controlling for these covariates. In contrast, the associations of Anaerococcus vaginalis, Dialister pneumosintes, Parvimonas micra, Peptostreptococcus anaerobius, Porphyromonas asaccharolytica and Prevotella intermedia remained robust, highlighting their future target potential. Finally, control individuals (age 22-80 years, mean 57.7 years, standard deviation 11.3) meeting criteria for colonoscopy (for example, through a positive fecal immunochemical test) but without colonic lesions are enriched for the dysbiotic Bacteroides2 enterotype, emphasizing uncertainties in defining healthy controls in cancer microbiome research. Together, these results indicate the importance of quantitative microbiome profiling and covariate control for biomarker identification in CRC microbiome studies.

Multitarget Stool RNA Test for Colorectal Cancer Screening

Importance

Noninvasive tests for colorectal cancer screening must include sensitive detection of colorectal cancer and precancerous lesions. These tests must be validated for the intended-use population, which includes average-risk individuals 45 years or older.

Objective

To evaluate the sensitivity and specificity of a noninvasive, multitarget stool RNA (mt-sRNA) test (ColoSense) test compared with results from a colonoscopy.

Design, Setting, and Participants

This phase 3 clinical trial (CRC-PREVENT) was a blinded, prospective, cross-sectional study to support a premarket approval application for a class III medical device. A total of 8920 participants were identified online using social media platforms and enrolled from June 2021 to June 2022 using a decentralized nurse call center. All participants completed the mt-sRNA test, which incorporated a commercially available fecal immunochemical test (FIT), concentration of 8 RNA transcripts, and participant-reported smoking status. Stool samples were collected prior to participants completing a colonoscopy at their local endoscopy center. The mt-sRNA test results (positive or negative) were compared with index lesions observed on colonoscopy. Over the course of 12 months, individuals 45 years and older were enrolled in the clinical trial using the decentralized recruitment strategy. Participants were enrolled from 49 US states and obtained colonoscopies at more than 3800 different endoscopy centers.

Main Outcomes and Measures

The primary outcomes included the sensitivity of the mt-sRNA test for detecting colorectal cancer and advanced adenomas and the specificity for no lesions on colonoscopy.

Results

The mean (range) age of participants was 55 (45-90) years, with 4% self-identified as Asian, 11% as Black, and 7% as Hispanic. Of the 8920 eligible participants, 36 (0.40%) had colorectal cancer and 606 (6.8%) had advanced adenomas. The mt-sRNA test sensitivity for detecting colorectal cancer was 94%, sensitivity for detecting advanced adenomas was 46%, and specificity for no lesions on colonoscopy was 88%. The mt-sRNA test showed significant improvement in sensitivity for colorectal cancer (94% vs 78%; McNemar P = .01) and advanced adenomas (46% vs 29%; McNemar P < .001) compared with results of the FIT.

Conclusions and Relevance

In individuals 45 years and older, the mt-sRNA test showed high sensitivity for colorectal neoplasia (colorectal cancer and advanced adenoma) with significant improvement in sensitivity relative to the FIT. Specificity for no lesions on colonoscopy was comparable to existing molecular diagnostic tests.

Trial Registration

ClinicalTrials.gov Identifier: NCT04739722.

A Machine Learning-Based System for Real-Time Polyp Detection (DeFrame): A Retrospective Study

BACKGROUND AND AIMS

Recent studies have shown that artificial intelligence-based computer-aided detection systems possess great potential in reducing the heterogeneous performance of doctors during endoscopy. However, most existing studies are based on high-quality static images available in open-source databases with relatively small data volumes, and, hence, are not applicable for routine clinical practice. This research aims to integrate multiple deep learning algorithms and develop a system (DeFrame) that can be used to accurately detect intestinal polyps in real time during clinical endoscopy.

METHODS

A total of 681 colonoscopy videos were collected for retrospective analysis at Xiangya Hospital of Central South University from June 2019 to June 2020. To train the machine learning (ML)-based system, 6,833 images were extracted from 48 collected videos, and 1,544 images were collected from public datasets. The DeFrame system was further validated with two datasets, consisting of 24,486 images extracted from 176 collected videos and 12,283 images extracted from 259 collected videos. The remaining 198 collected full-length videos were used for the final test of the system. The measurement metrics were sensitivity and specificity in validation dataset 1, precision, recall and F1 score in validation dataset 2, and the overall performance when tested in the complete video perspective.

RESULTS

A sensitivity and specificity of 79.54 and 95.83%, respectively, was obtained for the DeFrame system for detecting intestinal polyps. The recall and precision of the system for polyp detection were determined to be 95.43 and 92.12%, respectively. When tested using full colonoscopy videos, the system achieved a recall of 100% and precision of 80.80%.

CONCLUSION

We have developed a fast, accurate, and reliable DeFrame system for detecting polyps, which, to some extent, is feasible for use in routine clinical practice.

The feasibility of a fully synthetic and self-assembled peptide solution as submucosal injection material: a preliminary animal study

BACKGROUND AND AIM

An injection solution is required to create a submucosal cushion (SMC) for safe endoscopic resection procedures. The aim of this preliminary animal study was to clarify the safety and efficacy of a novel fully synthetic and self-assembled peptide (FSSP) solution as a submucosal injection material (SMIM).

METHOD

To compare the submucosal-lifting properties, 0.3% FSSP, Eleview®, sodium hyaluronate acid solution (SHA) and normal saline (NS) were randomly injected using an injection needle into the submucosa of exposed stomach and colon in five living dogs in a blind fashion. The mean height, and volume of SMCs were measured using a digital caliper immediately and 10, 20, 30, and 40 min after injecting each solution. All resected specimens were examined histopathologically.

RESULTS

In both the colon and stomach, ANOVA for repeated measures showed the significant interaction between time and solution for the time-dependent change in the height. In the colon, FSSP created significantly higher SMC than NS 20 min after injection (p = .0015) and Eleview® and NS 40 min after injection (p = .0009 and p = .0002). Furthermore, FSSP and SHA tended to maintain height and volume when compared to the other two solutions. In the stomach, FSSP and SHA tended to maintain height and volume when compared to the other two solutions. There were no significant differences between the histopathological finding and the injecting solutions used.

CONCLUSION

FSSP seems to be useful as a SMIM for endoscopic resection especially in the colon. Further studies are needed prior to clinical use of FSSP.

Colonoscopy Versus Fecal Immunochemical Test for Reducing Colorectal Cancer Risk: A Population-Based Case-Control Study

INTRODUCTION

Use of colonoscopy or the fecal immunochemical test (FIT) for colorectal cancer (CRC) prevention is supported by previous studies. However, there is little specific evidence regarding comparative effectiveness of colonoscopy or FIT for reducing CRC risk. In this study, we compared the association of CRC risk with colonoscopy and FIT using a nationwide database.

METHODS

This population-based case-control study used colonoscopy and FIT claims data from the Korean National Health Insurance System from 2002 to 2013. Data were analyzed from 61,221 patients with newly diagnosed CRC (case group) and 306,099 individuals without CRC (control group). Multivariable logistic regression models were used to evaluate the association between CRC and colonoscopy or FIT.

RESULTS

Colonoscopy was associated with a reduced subsequent CRC risk (adjusted odds ratio [OR] 0.29). Stronger associations were found between colonoscopy and distal CRC, compared with proximal CRC (0.24 vs 0.47). In an analysis stratified by sex, the association was weaker in female subjects compared with male subjects (0.33 vs 0.27). Any FIT exposure was associated with CRC risk with an OR of 0.74; this association was stronger for distal cancer. As the frequency of cumulative FIT assessments increased (from 1 to ≥5), the OR of FIT exposure for CRC gradually decreased from 0.81 to 0.45.

DISCUSSION

The association of colonoscopy or FIT with reduced CRC risk was stronger for distal CRC than for proximal CRC. FIT showed less CRC risk reduction than colonoscopy. However, as the frequency of cumulative FIT assessments increased, the association with CRC prevention became stronger.

Efficacy of Real-Time Computer-Aided Detection of Colorectal Neoplasia in a Randomized Trial

BACKGROUND & AIMS

One-fourth of colorectal neoplasias are missed during screening colonoscopies; these can develop into colorectal cancer (CRC). Deep learning systems allow for real-time computer-aided detection (CADe) of polyps with high accuracy. We performed a multicenter, randomized trial to assess the safety and efficacy of a CADe system in detection of colorectal neoplasias during real-time colonoscopy.

METHODS

We analyzed data from 685 subjects (61.32 ± 10.2 years old; 337 men) undergoing screening colonoscopies for CRC, post-polypectomy surveillance, or workup due to positive results from a fecal immunochemical test or signs or symptoms of CRC, at 3 centers in Italy from September through November 2019. Patients were randomly assigned (1:1) to groups who underwent high-definition colonoscopies with the CADe system or without (controls). The CADe system included an artificial intelligence-based medical device (GI-Genius, Medtronic) trained to process colonoscopy images and superimpose them, in real time, on the endoscopy display a green box over suspected lesions. A minimum withdrawal time of 6 minutes was required. Lesions were collected and histopathology findings were used as the reference standard. The primary outcome was adenoma detection rate (ADR, the percentage of patients with at least 1 histologically proven adenoma or carcinoma). Secondary outcomes were adenomas detected per colonoscopy, non-neoplastic resection rate, and withdrawal time.

RESULTS

The ADR was significantly higher in the CADe group (54.8%) than in the control group (40.4%) (relative risk [RR], 1.30; 95% confidence interval [CI], 1.14-1.45). Adenomas detected per colonoscopy were significantly higher in the CADe group (mean, 1.07 ±1.54) than in the control group (mean 0.71 ± 1.20) (incidence rate ratio, 1.46; 95% CI, 1.15-1.86). Adenomas 5 mm or smaller were detected in a significantly higher proportion of subjects in the CADe group (33.7%) than in the control group (26.5%; RR, 1.26; 95% CI, 1.01-1.52), as were adenomas of 6 to 9 mm (detected in 10.6% of subjects in the CADe group vs 5.8% in the control group; RR, 1.78; 95% CI, 1.09-2.86), regardless of morphology or location. There was no significant difference between groups in withdrawal time (417 ± 101 seconds for the CADe group vs 435 ± 149 for controls; P = .1) or proportion of subjects with resection of non-neoplastic lesions (26.0% in the CADe group vs 28.7% of controls; RR, 1.00; 95% CI, 0.90-1.12).

CONCLUSIONS

In a multicenter, randomized trial, we found that including CADe in real-time colonoscopy significantly increases ADR and adenomas detected per colonoscopy without increasing withdrawal time. ClinicalTrials.gov no: 04079478.

Variations in Screening Adenoma Detection Rate by Specialty of Physicians in a Predominately African American Population

BACKGROUND

Screening colonoscopy aims to interrupt the adenoma-carcinoma sequence by removing all precancerous adenomatous polyps. Adenomatous polyp detection rate (ADR) can vary between endoscopists as well as between race, age, and risk of colorectal cancer (CRC). The purpose of this study was to compare ADR among academic gastroenterologists (A-GI), non-A-GI, and surgeons for endoscopies performed in the same endoscopic suite of a large medical center with a predominately African American (AA) population.

METHODS

All screening colonoscopies performed in 2014 for patients aged 62-76 years were identified using the electronic medical records data. Patients with average risk and high risk of CRC defined as having a 'personal history of polyps' or 'family history of CRC', and history of ulcerative colitis and Fecal Occult Blood Test/Fecal Immunochemical Test (FOBT/FIT) positivity were included. Patients with incomplete colonoscopy (defined as failing to achieve cecal intubation or poor preparation) and unrecovered tissue biopsy were excluded. ADR was calculated for three groups of endoscopists: A-GIs, non-A-GIs, and surgeons.

RESULTS

A total of 573 screening colonoscopies was analyzed. The endoscopists comprised five A-GIs, eight non-A-GIs, and six surgeons. The majority of patients were of AA decent (71%), female (54%) with an average age of 66 years. Patients classified as average risk comprised 79% of the population. Most of the colonoscopies were performed by A-GI (n=339), followed by non-A-GI (n=144), and surgeons (n=90). The ADR for A-GI was 50% as compared to 32% for non-A-GI (p<0.001) and 25% for surgeons (p<0.001). Also, A-GI were more likely to identify ≥3 adenomas during screening colonoscopies. Significant differences were observed (p<0.001) in the mean time of colonoscopy for A-GI (30 mins) non-A-G (14 mins), and surgeons (18 mins).

CONCLUSION

Significant variation in the ADR between endoscopists belonging to different specialties were observed. Although all appear to achieve acceptable ADR (ie at least 25 for men and 15 for women), academic gastroenterologists had better performance than non-academic GI and surgeons. This may be explained by a significantly longer average duration of procedures for the highest ADR group.

Periodontitis is associated with an increased risk for proximal colorectal neoplasms

Interval colorectal cancers detected after colonoscopy are known to be highly associated with proximal colorectal neoplasms (CRNs). This cross-sectional study investigated whether periodontitis could be a risk factor for proximal CRNs in healthy individuals. A total of 2504 subjects who received a colonoscopy and dental exam were enrolled in this study. We divided the subjects into the periodontitis group (n = 216) and the control group (n = 2288). The periodontitis group was defined as subjects who had one or more teeth with a probing pocket depth (PPD) ≥4 mm. The prevalence of proximal CRNs was significantly higher in the periodontitis group (25.0%) than in the control group (12.3%) (P < 0.001). Independent risk factors for proximal CRNs in the multivariate analysis were periodontitis, smoking, age, waist circumference, and triglycerides, and those for proximal advanced CRNs were periodontitis, age, and family history of CRC. However, periodontitis was not a risk factor for overall CRNs and advanced CRNs. Periodontitis was associated with an increased risk of proximal CRNs (odds ratio [OR], 1.525; 95% confidence intervals [95% CI], 1.071–2.172) and proximal advanced CRNs (OR, 2.671; 95% CI, 1.088–6.560). Periodontitis might be associated with proximal CRNs and proximal advanced CRNs.

Polymorphism rs2682818 in miR-618 is associated with colorectal cancer susceptibility in a Han Chinese population

MicroRNAs (miRNAs), endogenous small noncoding RNAs (ncRNAs), play crucial roles in cancer development. Many studies have demonstrated that miRNAs can serve as diagnostic and therapeutic biomarkers for malignancies. Additionally, single nucleotide polymorphisms (SNPs) located in miRNA functional regions have been reported to be involved in cancer susceptibility. In this study, we investigated the associations between SNPs located in miRNA functional regions and colorectal cancer (CRC) susceptibility. We systematically screened all candidate miRNAs and their SNPs and then evaluated the relationships between the SNPs and CRC susceptibility in a Han Chinese population including 878 patients with CRC and 884 controls. Genotyping was performed by TaqMan assay. After comprehensively screening the miRNAs and SNPs, we elected to evaluate the association between SNP rs2682818 in miR‐618 and CRC susceptibility. We found that the AA and AC/AA genotypes of rs2682818 were associated with a decreased risk of CRC compared with the CC genotype (odds ratio (OR) = 0.54, 95% confidence interval (CI) = 0.37–0.79 for AA vs. CC in codominant model; OR = 0.82, 95% CI = 0.68–0.99 for AC/AA vs. CC in dominant model). However, we obtained no statically significant results in our subgroup analyses. SNP rs2682818 in miR‐618 has potential as a biomarker for individuals with high CRC susceptibility. Our findings need to be verified in studies including larger samples. Moreover, molecular functional studies of miR‐681 must be performed to confirm its relationship with CRC.

Colorectal endoscopic mucosal resection (EMR)

Colonoscopy has the benefit of detecting and treating precancerous adenomatous polyps and thus reduces mortality associated with CRC. Screening colonoscopy is the keystone for prevention of colorectal cancer. Over the last 20 years there has been increased in the management of large colorectal polyps from surgery to endoscopic removal techniques which is less invasive. Traditionally surgical resection was the treatment of choice for many years for larger polyps but colectomy poses significant morbidity of 14-46% and mortality of up to 7%. There are several advantages of endoscopic resection technique over surgery; it is less invasive, less expensive, has rapid recovery, and preserves the normal gut functions. In addition patient satisfaction and efficacy of EMR is higher with minor complications. Thus, this has facilitated the development of advanced resection technique for the treatment of large colorectal polyps called as endoscopic mucosal resection (EMR).

Clinical and Biological Features of Interval Colorectal Cancer

Interval colorectal cancer (I-CRC) is defined as a CRC diagnosed within 60 months after a negative colonoscopy, taking into account that 5 years is the "mean sojourn time." It is important to prevent the development of interval cancer. The development of interval colon cancer is associated with female sex, old age, family history of CRC, comorbidities, diverticulosis, and the skill of the endoscopist. During carcinogenesis, sessile serrated adenomas/polyps (SSA/Ps) share many genomic and colonic site characteristics with I-CRCs. The clinical and biological features of I-CRC should be elucidated to prevent the development of interval colon cancer.

Quality measures for colonoscopy: where should we be in 2015?

Colonoscopy is an effective colorectal cancer (CRC) screening and prevention modality as evidenced by a 30-year decline in both incident colon cancers and CRC mortality in the USA. The USA is unique among the developed countries in its use of colonoscopy as the most common method to screen for CRC. Individual patients gain maximum value from their colonoscopy experience when they undergo a comfortable exam that is of highest quality, during which all polyps are found and removed safely and completely, where their physicians adhere to all appropriate guidelines and when they (or their insurance) pay a reasonable amount for their care. Colonoscopy "quality" publications to date have been focused on how to improve the individual physician's procedural results and this narrow focus has birthed an entire industry (usually based on entering data into a national registry) that is focused on demonstrating a physician's success in achieving a certain threshold performance metric that is usually (a) marginally related to true health outcomes, (b) can be captured from the myriad electronic medical records (EMR) in existence today, and (c) is attainable by most practicing gastroenterologists. Medical societies have worked diligently to link these registries and recognition programs to commercial or federal payer-based incentive funds. As health care reform drives massive consolidation of delivery systems and reimbursement moves toward population-level two-sided financial risk models, our current measurement infrastructure will become irrelevant. The focus on "value" and the Triple Aim will drive development of a radically different approach. The process by which individual gastroenterologists (or practices) demonstrate the value of colonoscopy as a colorectal cancer (CRC) prevention tool will change dramatically. Essentially, six measures will be reported by a health system: (1) percent of eligible population screened, (2) access to colonoscopy services, (3) complication rates, (4) patient experience scores, (5) episode (bundle) cost, and (6) frequency with which interval cancers occur after a colonoscopy exam (likely using a 3-year interval). Each gastroenterologist within a health system will be evaluated using familiar metrics (cecal intubation, withdrawal time, adenoma detection rate) but these results will likely be used internally to determine whether they are included in a provider network. If they continue to be used in commercial or government incentive programs, then the enterprise electronic medical record will be constructed to populate external programs directly. Population-level metrics (listed above) will determine whether higher cost provider networks (including academic health centers) who might deliver better health outcomes can compete successfully for regional market share with lower cost providers. This article will outline a plan for a health system initiative focused on provision of colonoscopy for CRC prevention; a plan that will help a group of gastroenterologists (whether employed within a health system or independent) demonstrate why they should be a preferred provider and whether they will survive and thrive in the coming world of accountable care.

Outcomes of endoscopic treatment of second recurrences of large nonpedunculated colorectal adenomas

BACKGROUND AND AIMS

Piecemeal endoscopic mucosal resection (EMR) of large nonpedunculated colorectal adenomas is associated with significant recurrence rates. After salvage endoscopic treatment of recurrences, there is a significant rate of second recurrences. There is a paucity of data on the efficacy and safety of continued endoscopic treatment after a second recurrence.

METHODS

Consecutive patients with recurrent adenomas after initial piecemeal EMR of nonpedunculated colorectal adenomas >2 cm were reviewed. We assessed the feasibility, safety and efficacy of continued endoscopic treatment in these patients.

RESULTS

Sixty-four patients with 70 recurrent lesions were identified. All were retreated endoscopically. Follow-up colonoscopy (mean interval 6.4 months) was performed on 62/70 lesions (89 %), and a second recurrence was found in 21/62 (34 %). One patient underwent surgery for a circumferential adenoma of the ileocecal valve. The other 20 lesions were treated endoscopically. Follow-up colonoscopy was performed on 15/20 (75 %) and demonstrated a third recurrence in 3/15 (20 %). One was a deep T1 cancer; curative surgery was performed. The other two patients each had one additional endoscopic treatment and both had no recurrence on subsequent colonoscopy. There were two complications: Both were delayed bleeds after treatment of the first recurrence. A mean of 1.3 endoscopic procedures was required to achieve a cure (range 1-3) for recurrent adenomas after piecemeal EMR.

CONCLUSION

Endoscopic treatment of patients with second recurrences is safe and effective, but is associated with a significant rate of additional recurrences. Continued endoscopic treatment of patients with multiple recurrences is associated with high cure rates, low complication rates and a low risk of progression to malignancy.

Administrative Database Research Overestimates the Rate of Interval Colon Cancer

GOALS

Our study reexamines the prevalence of interval colorectal cancer (I-CRC) by manually reviewing CRC cases at a single institution.

BACKGROUND

In 2% to 8% of patients with CRC, diagnosis occurs during the interval 6 to 36 months after a cancer-free colonoscopy. Rates are often determined by linking the date of colonoscopy with cancer registry information.

STUDY

We examined all colonoscopies from 1993 to 2011. These examinations were linked with Pennsylvania Cancer Registry data. Matched charts were manually reviewed. We determined whether the CRC was "prevalent" or, for patients with a previous colonoscopy, whether they were interval or noninterval based on time from last colonoscopy. For interval cases, we identified "administrative errors" that could falsely increase the number of reported I-CRC.

RESULTS

Over the study period, 43,661 colonoscopies were performed, with 1147 (2.6%) positive for CRC after excluding cases (n=52) in which patients had IBD, previous surgery, or nonadenocarcinoma malignancy. Prevalent CRCs totaled 1062 (92.6%). Noninterval CRCs (diagnosed over 36 mo from index colonoscopy) were present in 40 (3.5%). There remained 45 (3.9%) potential I-CRC cases. However, after manual review, 21 cases were found to be administrative errors. Therefore, the accurate proportion of colonoscopies that found an I-CRC was 2.1% (95% confidence interval, 1.5%-3.2%).

CONCLUSIONS

The prevalence of I-CRC at our institution before adjustment was comparable with previously reported rates. This proportion was 47% lower after adjusting for administrative errors placing our figure at the lower end of reported I-CRC incidence. Reported rates of I-CRC may be falsely elevated due to errors unique to merging administrative databases.

Colonoscopy quality assessment

Colonoscopy is the cornerstone of colorectal cancer screening programs. There is significant variability in the quality of colonoscopy between endoscopists. Colonoscopy quality assessment tracks various metrics to improve the effectiveness of colonoscopy, aiming at reducing the incidence and mortality from colorectal cancer. Adenoma detection rate is the prime metric, because it is associated with the risk of interval cancer. Implementing processes to measure and improve the adenoma detection rate is essential to improve the quality of colonoscopy.

How can screening colonoscopy be optimized?

Since the implementation of screening programmes, both the incidence and mortality of colorectal cancer have been decreasing. The choice of the preferred screening tool, however, is divergent and the adherence to screening programmes in most countries is still low. Cancer detection tests such as the guaiac faecal occult blood test (gFOBT) and the immunohistochemical FOBT (iFOBT) achieve higher acceptance than endoscopy. The sensitivity and specificity of iFOBT are higher than those of gFOBT, but gFOBT is cheaper and easier to perform. Endoscopic screening, which represents cancer prevention tests, has higher sensitivity for premalignant lesions than gFOBT and iFOBT and enables diagnosis and therapy in one single procedure. Since screening colonoscopy and sigmoidoscopy are invasive procedures with potentially severe adverse events, the highest possible quality must be provided. High-tech equipment, experience, training, quality control programmes, excellent bowel preparation and low adverse event rates are pivotal. Alternative screening tools such as CT colonography, barium enema CT and multitarget stool DNA tests have not been established as routine screening tools to date.

Predicting the risk of recurrent adenoma and incident colorectal cancer based on findings of the baseline colonoscopy

Objectives:

The decision tree underlying current practice guidelines for post polypectomy surveillance relies on risk stratification based on predictive attributes gleaned from adenomas removed on screening colonoscopy examination. Our primary aim was to estimate the magnitude of association between baseline adenoma attributes and the risk of adenoma recurrence and invasive colorectal adenocarcinoma (CRC). Our secondary aims were to estimate the adenoma detection rate (ADR) of surveillance compared with screening colonoscopies and describe time trends in preventive colonoscopy utilization.

Methods:

We used prospective analyses of retrospectively collected clinical data from electronic health records. A cohort of primary care patients eligible for colorectal cancer screening was assembled encompassing 110,452 subjects, of which 3,300 had adenomas removed on screening examination. Of those patients who had a follow-up surveillance colonoscopy (defined as a patient with a documented adenoma on prior colonoscopy) recorded during the study period, 537 had a recurrent adenoma.

Results:

Of those recurrent adenomas, 354 had a high-risk attributes. High-risk attributes were described at >3 adenomas, at least one adenoma >10 mm in size, high-grade dysplasia, or villous features. The risk of developing invasive CRC among post polypectomy patients was significantly higher if the baseline adenomas displayed any of the following attributes: more numerous than 3 (4.3-fold higher risk, 95% confidence interval (CI) low, high 1.4, 12.9), larger than 10 mm in size (5.2-fold higher risk, 95% CI low, high 1.8, 15.1), high-grade dysplasia (13.2-fold risk, 95% CI low, high 2.8, 62.1), or villous features (7.4-fold higher risk, 95% CI low, high 2.5, 21.5). These attributes combined added a net value of 22.8% to the probability of correctly predicting CRC. There was a threefold increase in surveillance utilization relative to screening from 2005 to 2011. The ADR of surveillance (34.1%) was 1.5-fold higher than that of screening (23.1%).

Conclusions:

These results emphasize the need to mitigate excessive risk by performing timely surveillance colonoscopies in patients with baseline adenomas displaying high-risk attributes as recommended in practice guidelines.

Approaches for classifying the indications for colonoscopy using detailed clinical data

Background

Accurate indication classification is critical for obtaining unbiased estimates of colonoscopy effectiveness and quality improvement efforts, but there is a dearth of published systematic classification approaches. The objective of this study was to evaluate the effects of data-source and adjudication on indication classification and on estimates of the effectiveness of screening colonoscopy on late-stage colorectal cancer diagnosis risk.

Methods

This was an observational study in members of four U.S. health plans. Eligible persons (n = 1039) were age 55–85 and had been enrolled for 5 years or longer in their health plans during 2006–2008. Patients were selected based on late-stage colorectal cancer diagnosis in a case–control design; each case patient was matched to 1–2 controls by study site, age, sex, and health plan enrollment duration. Reasons for colonoscopies received in the 10-year period before the reference date were collected from three medical records sources (progress notes; referral notes; procedure reports) and categorized using an algorithm, with committee adjudication of some tests. We evaluated indication classification concordance before and after adjudication and used logistic regressions with the Wald Chi-square test to compare estimates of the effects of screening colonoscopy on late-stage colorectal cancer diagnosis risk for each of our data sources to the adjudicated indication.

Results

Classification agreement between each data-source and adjudication was 78.8-94.0% (weighted kappa = 0.53-0.72); the highest agreement (weighted kappa = 0.86-0.88) was when information from all data sources was considered together. The choice of data-source influenced the association between screening colonoscopy and late-stage colorectal cancer diagnosis; estimates based on progress notes were closest to those based on the adjudicated indication (% difference in regression coefficients = 2.4%, p-value = 0.98), as compared to estimates from only referral notes (% difference in coefficients = 34.9%, p-value = 0.12) or procedure reports (% difference in coefficients = 27.4%, p-value = 0.23).

Conclusion

There was no single gold-standard source of information in medical records. The estimates of colonoscopy effectiveness from progress notes alone were the closest to estimates using adjudicated indications. Thus, the details in the medical records are necessary for accurate indication classification.

Colonoscopy and colorectal cancer incidence and mortality

There is substantial indirect evidence for the effectiveness of colonoscopy in reducing colorectal cancer incidence and mortality. However, several recent studies have raised questions on the magnitude of effect for right-sided colorectal cancers. Well-documented variation in outcomes when colonoscopy is performed by different groups of endoscopists suggests that the recent emphasis on the quality of the procedures should lead to improved outcomes after colonoscopy including reduction in incidence and mortality due to right-sided colorectal cancers.

Factors associated with the risk of adenoma recurrence in distal and proximal colon

BACKGROUND/AIMS

Colonoscopy may be less effective in preventing cancer in the proximal colon. We evaluated whether risk factors for adenoma recurrence exhibit differential effect on adenoma recurrence by colon subsite.

METHODS

We examined the association of age, sex, body mass index, smoking status and use of nonsteroidal anti-inflammatory drugs (NSAIDs) on proximal and distal adenoma recurrence among 1,864 participants in the Polyp Prevention Trial. We used multinomial logistic regression models to calculate the relative risk ratios (RRR) and 95% CI.

RESULTS

733 (39.3%) participants had adenoma recurrence (228 distal only, 369 proximal only and 136 synchronous proximal and distal adenoma). When compared to participants without adenoma recurrence, no factor was associated with an increased risk of distal only adenoma recurrence. Age 65-69 years (RRR = 1.47, 95% CI 1.00-2.16), age ≥70 years (RRR = 2.24, 95% CI 1.57-3.20), and male sex (RRR = 1.73, 95% CI 1.32-2.27) were positively associated with proximal only adenoma recurrence. NSAIDs use was associated with a reduced risk of adenoma recurrence by similar magnitude in distal (RRR = 0.78, 95% CI 0.58-1.07) and proximal colon (RRR = 0.77, 95% CI 0.60-1.00).

CONCLUSIONS

We did not find any modifiable risk factor that differentially increases proximal as compared to distal adenoma recurrence to be clinically useful for targeted intervention.

Meta-analysis: adherence to colorectal cancer screening and the detection rate for advanced neoplasia, according to the type of screening test

BACKGROUND

A variety of tests have been proposed for colorectal cancer (CRC), giving rise to uncertainty regarding the optimal approach. The efficacy and effectiveness of different tests are related to both screened participation and the detection rate.

AIM

To perform a meta-analysis on adherence and detection rates of CRC screening tests.

METHODS

Relevant publications were identified by MEDLINE/EMBASE and other databases for the period 1999-2012. A previous systematic review was used for the period before 1966-1999. RCTs and controlled studies including a direct comparison of the uptake rates among different options for CRC screening were included. Adherence and detection rates for advanced neoplasia and cancer were extracted. Risk for bias was ascertained according to CONSORT guidelines. Forrest plots were produced based on random-effect models.

RESULTS

Fourteen studies provided data on 197 910 subjects. Endoscopic strategies were associated with a lower participation (RR: 0.67, 95% CI: 0.56, 0.80) rate, but a higher detection rate of advanced neoplasia (RR: 3.21, 95% CI: 2.38, 4.32) compared with faecal tests. FIT was superior to g-FOBT with regard to both adherence (RR: 1.16, 95% CI 1.03, 1.30) and detection of advanced neoplasia (RR: 2.28, 95% CI 1.68, 3.10) and cancer (RR: 1.96, 95% CI: 1.2, 3.2).

CONCLUSION

The superior accuracy of endoscopy compared with faecal tests minimised any impact of the participation rate in determining the detection rate of advanced neoplasia in a screening setting.

Contribution of behavioral risk factors and obesity to socioeconomic differences in colorectal cancer incidence

BACKGROUND

Health behaviors are known risk factors for colorectal cancer and are more common in low socioeconomic status (SES) populations. We evaluated the extent to which behavioral risk factors and body mass index (BMI) explain SES disparities in colorectal cancer incidence, overall and by tumor location.

METHODS

We analyzed prospective National Institutes of Health-AARP Diet and Health Study data on 506 488 participants who were recruited in 1995-1996 from six US states and two metropolitan areas and followed through 2006. Detailed baseline data on risk factors for colorectal cancer, including health behaviors, were obtained using questionnaires. SES was measured by self-reported education and census-tract data. The outcome was primary incident invasive colorectal adenocarcinoma. Poisson regression was used to estimate the association between SES and risk of incident colorectal cancer, with adjustment for age, sex, race and ethnicity, family history, and state of residence. The model estimates were used to derive percentage mediation by behavioral risk factors; bias-corrected 95% confidence intervals were obtained through bootstrap techniques.

RESULTS

Seven-thousand six-hundred seventy-six participants developed colorectal cancer during follow-up. SES differences in prevalence of physical inactivity, unhealthy diet, smoking, and unhealthy weight each explained between 11.3% (BMI) and 21.6% (diet) of the association between education and risk of colorectal cancer and between 8.6% (smoking) and 15.3% (diet) of the association between neighborhood SES and risk of colorectal cancer. Health behaviors and BMI combined explained approximately 43.9% (95% CI = 35.1% to 57.9%) of the association of education and 36.2% (95% CI = 28.0% to 51.2%) of the association of neighborhood SES with risk of colorectal cancer. The percentage explained by all factors and BMI combined was largest for right colon cancers and smallest for rectal cancers.

CONCLUSION

A substantial proportion of the socioeconomic disparity in risk of new-onset colorectal cancer, and particularly of right colon cancers, may be attributable to the higher prevalence of adverse health behaviors in low-SES populations.

Concerns and challenges in flexible sigmoidoscopy screening

In 1992, two well-conducted case-control studies used data from two different health maintenance organizations and demonstrated a 59-79% reduction in mortality from colorectal cancer (CRC) following exposure to sigmoidoscopy. These studies highlight the possibility of reducing mortality from CRC using population-based endoscopic screening. The development of fiber optics improved the technology, and the ease of performing flexible sigmoidoscopy (FS) with widespread adoption of this screening modality. To date, FS is the only endoscopic screening modality that has been shown to reduce mortality in randomized clinical trials. This article reviews the development of sigmoidoscopy, its use in CRC screening and the current reduced role of this proven screening modality, and explores new frontiers for population-based FS screening.

Neighborhood socioeconomic status and use of colonoscopy in an insured population--a retrospective cohort study

BACKGROUND

Low-socioeconomic status (SES) is associated with a higher colorectal cancer (CRC) incidence and mortality. Screening with colonoscopy, the most commonly used test in the US, has been shown to reduce the risk of death from CRC. This study examined if, among insured persons receiving care in integrated healthcare delivery systems, differences exist in colonoscopy use according to neighborhood SES.

METHODS

We assembled a retrospective cohort of 100,566 men and women, 50-74 years old, who had been enrolled in one of three US health plans for ≥1 year on January 1, 2000. Subjects were followed until the date of first colonoscopy, date of disenrollment from the health plan, or December 31, 2007, whichever occurred first. We obtained data on colonoscopy use from administrative records. We defined screening colonoscopy as an examination that was not preceded by gastrointestinal conditions in the prior 6-month period. Neighborhood SES was measured using the percentage of households in each subject's census-tract with an income below 1999 federal poverty levels based on 2000 US census data. Analyses, adjusted for demographics and comorbidity index, were performed using Weibull regression models.

RESULTS

The average age of the cohort was 60 years and 52.7% were female. During 449,738 person-years of follow-up, fewer subjects in the lowest SES quartile (Q1) compared to the highest quartile (Q4) had any colonoscopy (26.7% vs. 37.1%) or a screening colonoscopy (7.6% vs. 13.3%). In regression analyses, compared to Q4, subjects in Q1 were 16% (adjusted HR = 0.84, 95% CI: 0.80-0.88) less likely to undergo any colonoscopy and 30%(adjusted HR = 0.70, CI: 0.65-0.75) less likely to undergo a screening colonoscopy.

CONCLUSION

People in lower-SES neighborhoods are less likely to undergo a colonoscopy, even among insured subjects receiving care in integrated healthcare systems. Removing health insurance barriers alone is unlikely to eliminate disparities in colonoscopy use.

Socioeconomic status and the risk of colorectal cancer: an analysis of more than a half million adults in the National Institutes of Health-AARP Diet and Health Study

BACKGROUND

No previous prospective US study has examined whether the incidence of colorectal cancer (CRC) is disproportionately high in low socioeconomic status (SES) populations of both men and women. This study examined the relationship between both individual and area-level SES and CRC incidence, overall and by tumor location.

METHODS

Data were obtained from the ongoing prospective National Institutes of Health-AARP Diet and Health Study of persons (50-71 years old) who resided in 6 US states and 2 metropolitan areas at baseline in 1995-1996. Incident CRCs were ascertained from tumor registries through December 2006. SES was measured by self-reported education and census-tract socioeconomic deprivation. Baseline and follow-up questionnaires collected detailed information on individual-level CRC risk factors including family history and health behaviors.

RESULTS

Among 506,488 participants analyzed, 7676 were diagnosed with primary invasive colorectal adenocarcinomas: 44.6% [corrected] in the right colon, 26.7% in the left colon, and 25.9% in the rectum. The overall incidence of CRC was significantly higher among people who had low educational level or lived in low-SES neighborhoods, relative to respective highest-SES groups, even after accounting for other risk factors. These associations were stronger in the rectum than in left or right colon. In the right colon, there were no significant SES differences by either SES measure after accounting for covariates.

CONCLUSIONS

SES, assessed by either individual-level education or neighborhood measures, was associated with risk of CRC even after accounting for other risk factors. The relationship between SES and CRC was strongest in the rectum and weakest in the right colon.

A morphologic analysis of sessile serrated polyps observed during routine colonoscopy (with video)

BACKGROUND

Proximal colorectal cancer may arise from sessile serrated polyps (SSPs), which are often inconspicuous during colonoscopy. The gross morphologic characteristics of SSPs have not been systematically described, and this omission may contribute to colonoscopists overlooking them.

OBJECTIVES

To analyze the gross morphologic characteristics of SSPs detected during routine colonoscopy.

DESIGN

Retrospective analysis of high-resolution endoscopic video clips depicting SSPs in situ.

SETTING

Outpatient gastroenterology practice.

PATIENTS

A total of 124 subjects undergoing surveillance or screening colonoscopy after split-dose bowel preparation.

INTERVENTIONS

Analysis of 158 SSPs performed by using validated descriptors.

MAIN OUTCOME MEASUREMENTS

The prevalence of morphologic characteristics related to polyp shape, color, and texture.

RESULTS

A total of 158 SSPs were studied. For 7 visual descriptors, a κ coefficient of ≥ 0.7 was achieved, indicating good to excellent intraobserver agreement. The most prevalent visual descriptors were the presence of a mucous cap (63.9%), rim of debris or bubbles (51.9%), alteration of the contour of a fold (37.3%), and interruption of the underlying mucosal vascular pattern (32.3%). The most common "sentinel signs" were the presence of a mucous cap and alteration of the contour of a mucosal fold (each 24.6%), rim of debris or bubbles (21.7%), and a dome-shaped protuberance (20.3%). When comparing SSPs with adenomatous polyps, the frequencies of 5 of 7 morphologic characteristics and the distribution of sentinel signs differed (P < .01).

LIMITATIONS

Single-site, retrospective analysis.

CONCLUSIONS

SSPs exhibit distinct, variable morphologic characteristics. Many do not display classic features such as a mucous cap. Enhanced appreciation of these morphologic characteristics may improve SSP detection and thereby colorectal cancer prevention.

Likelihood of missed and recurrent adenomas in the proximal versus the distal colon

BACKGROUND

Colonoscopy may be less efficacious in reducing colorectal cancer mortality in the proximal compared with the distal colon. A greater likelihood for missed and recurrent adenomas in the proximal colon may contribute to this phenomenon.

OBJECTIVE

To examine whether a proximal adenoma is associated with the risk and location of missed and recurrent adenomas.

DESIGN

Prospective.

SETTING

Polyp Prevention Trial.

PARTICIPANTS

A total of 1864 patients with an adenoma at baseline underwent a follow-up colonoscopy 4 years later (adenoma recurrence). Of these, 1731 underwent a clearing colonoscopy 1 year after the baseline examination (missed adenoma).

MAIN OUTCOME MEASUREMENTS

Association of baseline adenoma location with the risk and location of adenomas found at colonoscopy performed 1 year and 4 years later.

RESULTS

At the year 1 colonoscopy, 598 patients (34.6%) had an adenoma (missed adenoma). Compared with those with a distal-only adenoma at baseline, patients with a proximal-only adenoma at baseline were more likely to have any missed adenomas (relative risk [RR] 1.28; 95% CI, 1.09-1.49) and a proximal-only missed adenoma (RR 2.05; 95% CI, 1.49-2.80). At the year 4 colonoscopy, 733 patients (39.3%) had adenoma recurrence. Patients with a baseline proximal-only adenoma were more likely to have any adenoma recurrence (RR 1.14; 95% CI, 1.00-1.31) and a proximal-only adenoma recurrence (RR 1.52; 95% CI, 1.15-2.02). Sensitivity analyses involving missed adenomas did not materially affect the risk or location of recurrent adenomas at year 4 colonoscopy.

LIMITATION

Lesions may still be missed on repeated colonoscopies.

CONCLUSIONS

Missed and recurrent adenomas are more likely to be in the proximal colon.

Detection of colorectal neoplasia by colonoscopy in average-risk patients age 40-49 versus 50-59 years

BACKGROUND

The USPSTF recommends beginning colorectal cancer screening at age 50. A recent study showed prevalence of colorectal adenomas among individuals aged 40-49 was similar to that among those aged 50-59.

AIM

To assess the prevalence of colorectal neoplasia, detected during colonoscopy, by age among average-risk patients.

METHODS

Nine-hundred and ninety-four colonoscopies were analyzed (247 ages 40-49, 747 ages 50-59). We included consecutive patients of ages 40-59 undergoing their first colonoscopy. Colonoscopies that did not reach the cecum and patients at increased risk of colorectal cancer were excluded. The primary endpoint was the prevalence of colorectal neoplasia by age. Secondary endpoints included the prevalence of colorectal neoplasia by gender, ethnicity, and BMI.

RESULTS

The prevalence of colorectal neoplasia was 12.1% in patients aged 40-49 and 22.6% in those aged 50-59. Compared with individuals aged 40-49 there was a significantly greater prevalence of adenomas (chi-squared = 12.72, P = 0.0004) and of advanced adenomas or cancer (chi-squared = 5.73, P = 0.01) in individuals aged 50-59. After adjusting for gender, race, and BMI the effect of age remained significant (OR 0.5, 95% CI 0.33-0.76). Higher BMI was associated with increased risk of colorectal neoplasia (OR 1.03, 95% CI 1.00-1.06). The number that had to be screened to detect one advanced lesion in the 40-49 age group was 49 compared with 20 in those aged 50-59.

CONCLUSION

Individuals aged 40-49 have a lower but measurable risk of colorectal neoplasia compared with those aged 50-59. Although there may be population subgroups for which screening below the age of 50 may be indicated, our results do not support lowering the age threshold for colonoscopy in the general population.

The reduction in colorectal cancer mortality after colonoscopy varies by site of the cancer

BACKGROUND & AIMS

There are limited data on mortality from colorectal cancer (CRC) among patients who have received colonoscopy examinations. We sought to determine CRC mortality among persons undergoing colonoscopies compared with the general population.

METHODS

We identified all individuals who had a colonoscopy as their first lower gastrointestinal endoscopy from April 1, 1987, to September 30, 2007 (24,342 men and 30,461 women), based on information from Manitoba's provincial physicians' billing claims database. Patients were followed until March 31, 2008, death, or migration out of the province (310,718 person-years). Individuals less than 50 years of age or more than 80 years of age at the index colonoscopy or those with prior sigmoidoscopy, inflammatory bowel disease, resective colorectal surgery, or CRC were excluded. CRC mortality after the index colonoscopy was compared with that of the general population by standardized mortality ratios (SMRs). Stratified analyses were performed to determine CRC mortality for different age groups at index colonoscopy and sex, duration of follow-up, medical specialty of the endoscopist, and site of CRC.

RESULTS

There was a 29% reduction in overall CRC mortality (SMR, 0.71; 95% confidence interval [CI], 0.61-0.82], a 47% reduction in mortality from distal CRC (SMR, 0.53; 95% CI, 0.42-0.67), and no reduction in mortality from proximal CRC (SMR, 0.94; 95% CI, 0.77-1.17). The reduction in mortality from distal CRC remained significant for follow-up beyond 10 years (SMR, 0.53; 95% CI, 0.31-0.84).

CONCLUSIONS

In Manitoba, colonoscopies significantly reduce mortality from CRC, but the benefit is not uniform for colorectal tumors that arise in different areas of the colon.

FIT: a valuable but underutilized screening test for colorectal cancer-it's time for a change

Although fecal immunochemical tests (FITs) have been used for colorectal cancer (CRC) screening in several countries for years, this has not been the case in the United States. The reasons for this are multifactorial, but if the United States hopes to increase screening rates, the evidence is in regarding FIT's benefits and potential. A publication in this issue of the American Journal of Gastroenterology provides "gold standard" evidence of its superiority over the standard guaiac test and opens opportunities for investigators to discover the most effective uses of this test for population screening.

Cost-effectiveness of colorectal cancer screening with computed tomography colonography according to a polyp size threshold for polypectomy

OBJECTIVE

Computed tomography colonography (CTC) has an acceptable accuracy in detecting colonic lesions, especially for polyps at least 6 mm. The aim of this analysis is to determine the cost-effectiveness of population-based screening for colorectal cancer (CRC) using CTC with a polyp size threshold.

METHODS

The cost-effectiveness ratios of CTC performed at 50, 60 and 70 years old, without (PL strategy) or with (TS strategy) polyp size threshold were compared using a Markov process. Incremental cost-effectiveness ratios (ICER) were calculated per life-years gained (LYG) for a time horizon of 30 years.

RESULTS

The ICER of PL and TS strategies were 12 042 and 2765 euro/LYG associated to CRC prevention rates of 37.9 and 36.5%. The ICER of PL and TS strategies dropped to 9687 and 1857 euro/LYG when advanced adenoma (AA) prevalence increased from 6.9 to 8.6% for male participants and 3.8-4.9% for female participants or to 9482 and 2067 euro/LYG when adenoma and AA annual recurrence rates dropped to 3.2 and 0.25%. The ICER for PL and TS strategies decreased to 7947 and 954 euro/LYG or when only two CTC were performed at 50 and 60-years-old. Conversely, the ICER did not significantly change when varying population participation rate or accuracy of CTC.

CONCLUSION

CTC with a 6 mm threshold for polypectomy is associated to a substantial cost reduction without significant loss of efficacy. Cost-effectiveness depends more on the AA prevalence or transition rate to CRC than on CTC accuracy or screening compliance.

Quality indicators for colonoscopy and the risk of interval cancer

BACKGROUND

Although rates of detection of adenomatous lesions (tumors or polyps) and cecal intubation are recommended for use as quality indicators for screening colonoscopy, these measurements have not been validated, and their importance remains uncertain.

METHODS

We used a multivariate Cox proportional-hazards regression model to evaluate the influence of quality indicators for colonoscopy on the risk of interval cancer. Data were collected from 186 endoscopists who were involved in a colonoscopy-based colorectal-cancer screening program involving 45,026 subjects. Interval cancer was defined as colorectal adenocarcinoma that was diagnosed between the time of screening colonoscopy and the scheduled time of surveillance colonoscopy. We derived data on quality indicators for colonoscopy from the screening program's database and data on interval cancers from cancer registries. The primary aim of the study was to assess the association between quality indicators for colonoscopy and the risk of interval cancer.

RESULTS

A total of 42 interval colorectal cancers were identified during a period of 188,788 person-years. The endoscopist's rate of detection of adenomas was significantly associated with the risk of interval colorectal cancer (P=0.008), whereas the rate of cecal intubation was not significantly associated with this risk (P=0.50). The hazard ratios for adenoma detection rates of less than 11.0%, 11.0 to 14.9%, and 15.0 to 19.9%, as compared with a rate of 20.0% or higher, were 10.94 (95% confidence interval [CI], 1.37 to 87.01), 10.75 (95% CI, 1.36 to 85.06), and 12.50 (95% CI, 1.51 to 103.43), respectively (P=0.02 for all comparisons).

CONCLUSIONS

The adenoma detection rate is an independent predictor of the risk of interval colorectal cancer after screening colonoscopy.

Colorectal cancer screening in evolution: Japan and the USA

Colorectal cancer (CRC) is one of the most common cancers in both Japan and the USA. Age-adjusted incidence of CRC has been in decline in the USA since 1985, while rates in Japan have been increasing. The decline in the USA is commonly attributed to CRC screening programs but there is little direct evidence to support this assertion. The current screening recommendations in the USA cover several options including colonoscopy and computerized tomographic colonography (CTC). The Japanese CRC screening program is centered on fecal immunochemistry testing (FIT). The US government Medicare program's approval of colonoscopy as a primary screening test has lead to a large increase in the number of patients undergoing the procedure. However, the benefit achieved from this change in screening program emphasis is not clear. Simulation models demonstrate that a screening program centered on FIT achieves 94% of the benefit that an all-colonoscopy program is able to accomplish but at a lower cost per life year gained. Clinical studies of colonoscopy have failed to demonstrate the 76-90% declines in CRC incidence predicted by the National Polyp Study published in 1993. A potential reason for this failure is the quality of colonoscopy performance. Until more compelling data becomes available demonstrating the utility of colonoscopy as a primary screening modality, there is little incentive to alter the proven cost-effective approach to CRC screening currently in practice in Japan.

A retrograde-viewing device improves detection of adenomas in the colon: a prospective efficacy evaluation (with videos)

BACKGROUND

Colonoscopy may fail to detect neoplasia located on the proximal sides of haustral folds and flexures. The Third Eye Retroscope (TER) provides a simultaneous retrograde view that complements the forward view of a standard colonoscope.

OBJECTIVE

To evaluate the added benefit for polyp detection during colonoscopy of a retrograde-viewing device.

DESIGN

Open-label, prospective, multicenter study evaluating colonoscopy by using a TER in combination with a standard colonoscope.

SETTING

Eight U.S. sites, including university medical centers, ambulatory surgery centers, a community hospital, and a physician's office.

PATIENTS

A total of 249 patients (age range 55-80 years) presenting for screening or surveillance colonoscopy.

INTERVENTIONS

After cecal intubation, the disposable TER was inserted through the instrument channel of the colonoscope. During withdrawal, the forward and retrograde video images were observed simultaneously on a wide-screen monitor.

MAIN OUTCOME MEASUREMENTS

The number and sizes of lesions (adenomas and all polyps) detected with the standard colonoscope and the number and sizes of lesions found only because they were first detected with the TER.

RESULTS

In the 249 subjects, 257 polyps (including 136 adenomas) were identified with the colonoscope alone. The TER allowed detection of 34 additional polyps (a 13.2% increase; P < .0001) including 15 additional adenomas (an 11.0% increase; P < .0001). For lesions 6 mm or larger, the additional detection rates with the TER for all polyps and for adenomas were 18.2% and 25.0%, respectively. For lesions 10 mm or larger, the additional detection rates with the TER for all polyps and for adenomas were 30.8% and 33.3%, respectively. In 28 (11.2%) individuals, at least 1 additional polyp was found with the TER. In 8 (3.2%) patients, the polyp detected with the TER was the only one found. Every polyp that was detected with the TER was subsequently located with the colonoscope and removed. For all polyps and for adenomas, the additional detection rates for the TER were 9.7%/4.1% in the left colon (the splenic flexure to the rectum) and 16.5%/14.9% in the right colon (the cecum to the transverse colon), respectively.

LIMITATIONS

There was no randomization or comparison with a separate control group.

CONCLUSIONS

A retrograde-viewing device revealed areas that were hidden from the forward-viewing colonoscope and allowed detection of 13.2% additional polyps, including 11.0% additional adenomas. Additional detection rates with the TER for adenomas 6 mm or larger and 10 mm or larger were 25.0% and 33.3%, respectively. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00657371.).

Predictors of colorectal cancer after negative colonoscopy: a population-based study

OBJECTIVES

A higher proportion of colorectal neoplasia among women occurs in the proximal colon, which might be more frequently missed by colonoscopy. There are no data on predictors of developing colorectal cancer (CRC) after a negative colonoscopy in usual clinical practice. We evaluated gender differences and predictors of CRC occurring after a negative colonoscopy.

METHODS

All individuals 40 years or older with negative colonoscopy were identified from Manitoba's provincial physicians' billing claims database. Individuals with less than 5 years of coverage by the provincial health plan, earlier CRC, inflammatory bowel disease, resective colorectal surgery, or lower gastrointestinal endoscopy were excluded. CRC risk after negative colonoscopy was compared to that in the general population by standardized incidence ratios. Cox regression analysis was performed to determine the independent predictors of CRC occurring after negative colonoscopy.

RESULTS

A total of 45,985 individuals (18,606 men; 27,379 women) were followed up for 229,090 person-years. After a negative colonoscopy, men had a 40-50% lower risk of CRC diagnosis through most of the follow-up time. Risk among women was similar to that of women in the general population in the first 3 years and then was 40-50% lower. Older subject age and performance of index colonoscopy by non-gastroenterologists were independent predictors for early/missed CRC (cancers occurring within 3 years of negative colonoscopy).

CONCLUSIONS

Women may have a higher rate of missed/early CRCs after negative colonoscopy. Predictors of missed/early CRCs after negative colonoscopy include older age and performance of index colonoscopy by a non-gastroenterologist.

Effect of screening colonoscopy on colorectal cancer incidence and mortality

BACKGROUND & AIMS

Colonoscopy is used widely for colorectal cancer (CRC) screening; however, its long-term impact on the incidence and mortality of CRC is not known.

METHODS

We assessed CRC incidence and mortality in a group of asymptomatic average-risk patients who underwent screening colonoscopy between 1989 and 1993 at a university hospital. By using standardized incidence ratios and standardized mortality ratios, we compared our observed CRC rates with expected rates from the Surveillance, Epidemiology, and End Results (SEER) data.

RESULTS

The cohort comprised 715 patients (mean age, 61 +/- 6.5 y; 59% male; 95% Caucasian) with 10,492 patient-years of follow-up. There were 12 cases of CRC: 5 found at baseline and 7 found after a median follow-up period of 8 years (range, 3-16 y). When the first 2 years of follow-up were excluded, there were 7 incident cases of CRC (95% confidence interval [CI], 2-13) over 9075 person-years of follow-up. The expected number based on SEER data was 21. The incidence rate was 0.77 cases per 1000 person-years, and the standardized incidence ratio was 0.33 (95% CI, 0.10-0.62), consistent with a relative risk reduction in CRC incidence of 67%. Three patients died from CRC (95% CI, 0-9). The expected number of deaths based on SEER data was 9. The mortality rate was 0.29 per 1000 person-years, and the standardized mortality ratio was 0.35 (95% CI, 0.0-1.06), consistent with a relative reduction in CRC death of 65%.

CONCLUSIONS

In this average-risk cohort, CRC incidence and mortality were reduced after screening colonoscopy. These results provide additional evidence for the effectiveness of colonoscopy as a primary CRC screening modality.

[Colorectal cancer screening programme in France, role of the National Institute of Cancer]

With almost 37,500 new cases per year and 17,000 deaths, colorectal cancer represents a major public health problem in France. A new stage in the fight against this cancer should be marked in 2009 with the widespread implementation of the colorectal cancer screening programme over the whole of the French territory. This population-based screening programme targets an eligible population of 16 million persons. The evaluation of the first 23 pilot districts allowed a standardization of the main quality and efficacy indicators. The implementation of the colorectal cancer screening programme relies on monitoring centres, usually one per district, set up for the national breast cancer screening programme. The programme refers to quality assurance guidelines and includes explicit policy with specified age categories, method, and interval for screening. A national screening training programme for newly districts joining the programme was implemented. A small number of laboratories have been selected for the programme on quality criteria. The French National Cancer Institute contributes to organization, information, guidelines, and research. The replacement of the guaiac test used in the French programme by an immunochemical test should be effective in the next few years.

PillCam Colon capsule endoscopy does not always complement incomplete colonoscopy

BACKGROUND

There are no data on the role of PillCam Colon capsule (PCC) endoscopy for examination of the colon in incomplete colonoscopy cases.

OBJECTIVE

To evaluate whether PCC endoscopy can complete colon examination after failure of conventional colonoscopy to visualize the cecum.

SETTING

Three tertiary centers.

STUDY DESIGN

Retrospective case series.

PATIENTS

Patients who underwent PCC endoscopy after incomplete colonoscopy from January to June 2008.

INTERVENTIONS

Conventional colonoscopy and PCC endoscopy.

RESULTS

By using PCC, we studied 12 patients who had incomplete colonoscopy. Six patients had an obstructing tumor of the left side of the colon, and, in 6 cases, there were technical difficulties to complete colonoscopy. PCC endoscopy visualized the rectum in 1 case. The capsule did not reach the site where colonoscopy stopped in 6 of the 12 cases, ie, 3 left sited tumors and 3 with technical difficulties. Moreover, in 1 of the 3 cases in which the capsule passed the site where colonoscopy stopped, poor bowel preparation precluded the accurate examination of the colon. Four patients underwent a third colon examination (3 barium enemas and 1 virtual CT colonoscopy). There were no adverse events related to PCC endoscopy.

LIMITATIONS

A retrospective study and a selected patient population. Data may not be applicable to other settings.

CONCLUSION

In this retrospective case series of patients with incomplete colonoscopy, PCC endoscopy did not always satisfactorily examine the colon.

[Colonoscopy, the primary tool for colonic screening]

Through an overview of the colonic screening methods, the authors study colonoscopy with high emphasis. Taking into consideration its high sensitivity and specificity in the detection of colorectal carcinomas and adenomas, as well as the possibility of adenoma removal through examination, colonoscopy is recommended to be applied as the primary colonic screening within the scope of a national screening program.