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Current management of diminutive colorectal polyps in Taiwan
Abstract
The majority of polyps detected during colonoscopy are diminutive polyps, for which the cost of pathological analysis is substantial. In our analysis of a screening cohort of 10 737 subjects undergoing screening colonoscopy, a total of 15 877 neoplastic lesions were detected, of which 10 816 (68.1%) were diminutive lesions. Of those diminutive lesions, 90 (0.83%) had a villous component, 14 (0.1%) had high-grade dysplasia, and none had invasive cancer. Only 1.3% of patients were advised to decrease their surveillance interval because of unfavorable histology. Laws regulating medical practice, uncertainty regarding the accuracy of endoscopic diagnosis of diminutive polyps outside of academic centers, and the relatively low cost of pathological analysis are among the barriers to adopting a ‘resect and discard’ practice in Taiwan.
... In our study, polyps' sizes that were less than or equal to 5 mm and from 6 to 9 mm represented most polyps that were identifiable during colonoscopy. This agrees with other studies [18,19]. We revealed that ∼82% of polyps less than or equal to 5 mm in size were NAPs, whereas ∼8% were AAs. ...
... All colorectal polyps are sent for pathologic interpretation to ensure a consistency of 90%. Cost-effectiveness analyses have revealed that employing the innovative endoscopic optical technology to diagnose colorectal polyps and adopting either the diagnosis-and-leave or resect-and-discard strategy are cost-effective [12][13][14][15][16][17]. Nevertheless, the current challenge in the use of innovative endoscopic optical technology to diagnose colorectal polyps is that not all endoscopists meet the standards recommended by the ASGE. ...
Colonoscopy screening and colonoscopic polypectomy can decrease the incidence and mortality rate of colorectal cancer (CRC). The adenoma detection rate and accuracy of diagnosis of colorectal polyp which vary in different experienced endoscopists have impact on the colonoscopy protection effect of CRC. The work proposed a colorectal polyp image detection and classification system through grayscale images and deep learning. The system collected the data of CVC-Clinic and 1000 colorectal polyp images of Linkou Chang Gung Medical Hospital. The red-green-blue (RGB) images were transformed to 0 to 255 grayscale images. Polyp detection and classification were performed by convolutional neural network (CNN) model. Data for polyp detection was divided into five groups and tested by 5-fold validation. The accuracy of polyp detection was 95.1% for grayscale images which is higher than 94.1% for RGB and narrow-band images. The diagnostic accuracy, precision and recall rates were 82.8%, 82.5% and 95.2% for narrow-band images, respectively. The experimental results show that grayscale images achieve an equivalent or even higher accuracy of polyp detection than RGB images for lightweight computation. It is also found that the accuracy of polyp detection and classification is dramatically decrease when the size of polyp images small than 1600 pixels. It is recommended that clinicians could adjust the distance between the lens and polyps appropriately to enhance the system performance when conducting computer-assisted colorectal polyp analysis.
... Diminutive (1-5 mm in size) and small (6-9 mm in size) colorectal polyps represent the majority of polyps that are identifiable during colonoscopy (25,26). A study from Taiwan revealed that 1.3% of the diminutive polyps had an advanced histology (25). ...
Increasing age is a risk factor for the development of colorectal adenomas and advanced adenomas. However, few studies have been published on the features of colorectal polyps in the elderly. The present study aimed to investigate the clinical, enteroscopic and pathological characteristics of colorectal polyps in Chinese elderly patients in a single center (The Central Hospital of Wuhan, Hubei, China). The endoscopic and pathological reports of colonoscopies performed in our center were retrospectively analyzed. A total of 7,795 consecutive patients referred for colonoscopy were evaluated between January 2013 and December 2014. Of the 297 who met the inclusion criteria, 279 polyps were observed in men and 230 in women. Of all the polyps, 263 were non-adenomatous polyps, 104 were non-advanced adenomas and 142 were advanced adenomas. 336 polyps were left-sided and 173 were right-sided. Polyps ≥10 mm were more likely to exhibit an adenomatous component and advanced features, and these findings continued to hold true when the size cut-off was set at 5 mm. The data shown in the present study have revealed that a significant number of polyps lie proximal to the splenic flexure. Thus, evaluation of the whole bowel is particularly important in elderly patients who are undergoing colonoscopy. In addition, the polyp size was associated with the presence of adenoma, and advanced component, diminutive and small polyps should not be ignored in elderly patients.
... According to the "Evidenced-Based Clinical Practice Guidelines for Management of Colorectal Polyps" edited by the Japanese Society of Gastroenterology, it is recommended that small lesions (≥6 mm in size) be treated with ER, whereas diminutive lesions other than nonpolypoid lesions that are difficult to distinguish from adenoma or carcinoma should not be treated with ER [8] because such lesions are rarely accompanied by high-grade adenoma/dysplasia (HGD) or other advanced adenoma [5,[7][8][9]. On the other hand, it has been reported that the incidence of TA with HGD is not different between diminutive and small TAs [10]. Why, then, should the Japanese guidelines recommend that small adenomatous polyps ≥6 mm in size be treated with ER? ...
Objective:
To evaluate the feasibility and safety of marking targeting biopsy (MTB) in the intraoperative localization value of colon polypectomy.
Methods:
The clinical data from patients with polyp of colon discovered under colonoscopy from January 2014 to January 2016 were retrospectively analyzed. A total of 87 patients conformed to the inclusion criteria, among them, 43 received colonoscopic polypectomy one week after MTB (MTB group), while 44 underwent colonoscopic polypectomy one week after conventional biopsy (conventional group). The time consumption in colonoscopic treatment, polypectomy rate and postoperative complications between two groups were compared.
Results:
The time consumed in operation in the MTB group was 25.5 (±8.6) minutes, while that in conventional group was 42.0 (±20.5) minutes, and the difference was statistically significant (P<0.01). There were a total of 86 polyps in the MTB group, among which 83 were removed, yielding the removal rate of 96.5%. There were altogether 88 polyps in the conventional group, among which 54 were removed, resulting in the removal rate of 61.4%, and the difference was statistically significant (P<0.05). three polyps in the MTB group were detached after MTB, or the wound surface became flat after gross polyp removal, and no polypectomy was required, but the marking targeting solution was clearly visible. two respective polyps in 12 cases in conventional group could not be found in colonoscopic treatment, and 10 of them had respective one polyp that could not be found again. 12 cases in MTB group suffered from abdominal pain after surgery, and no hemorrhage was seen intraoperatively and postoperatively. 10 cases in the conventional group had abdominal pain after surgery, and one case had delayed hemorrhage after surgery. The results between two groups displayed no statistical significance (P>0.05).
Conclusions:
The localization value of MTB in colon polypectomy is definitely feasible, safe and effective, which can greatly shorten the time of endoscopic colon polypectomy, mitigate patient sufferings, and reduce the incidence of false negative rate of polyp. It displays favorable clinical application value and is worthy of being promoted in clinic.
Main Recommendations
1 ESGE suggests that high definition endoscopy, and dye or virtual chromoendoscopy, as well as add-on devices, can be used in average risk patients to increase the endoscopist’s adenoma detection rate. However, their routine use must be balanced against costs and practical considerations.
Weak recommendation, high quality evidence.
2 ESGE recommends the routine use of high definition systems in individuals with Lynch syndrome.
Strong recommendation, high quality evidence.
3 ESGE recommends the routine use, with targeted biopsies, of dye-based pancolonic chromoendoscopy or virtual chromoendoscopy for neoplasia surveillance in patients with long-standing colitis.
Strong recommendation, moderate quality evidence.
4 ESGE suggests that virtual chromoendoscopy and dye-based chromoendoscopy can be used, under strictly controlled conditions, for real-time optical diagnosis of diminutive (≤ 5 mm) colorectal polyps and can replace histopathological diagnosis. The optical diagnosis has to be reported using validated scales, must be adequately photodocumented, and can be performed only by experienced endoscopists who are adequately trained, as defined in the ESGE curriculum, and audited.
Weak recommendation, high quality evidence.
5 ESGE recommends the use of high definition white-light endoscopy in combination with (virtual) chromoendoscopy to predict the presence and depth of any submucosal invasion in nonpedunculated colorectal polyps prior to any treatment.
Strong recommendation, moderate quality evidence.
6 ESGE recommends the use of virtual or dye-based chromoendoscopy in addition to white-light endoscopy for the detection of residual neoplasia at a piecemeal polypectomy scar site.
Strong recommendation, moderate quality evidence.
7 ESGE suggests the possible incorporation of computer-aided diagnosis (detection and characterization of lesions) to colonoscopy, if acceptable and reproducible accuracy for colorectal neoplasia is demonstrated in high quality multicenter in vivo clinical studies. Possible significant risks with implementation, specifically endoscopist deskilling and over-reliance on artificial intelligence, unrepresentative training datasets, and hacking, need to be considered.
Weak recommendation, low quality evidence.
Background and aims:
There is an increased risk of developing metachronous colorectal cancer (CRC) in the remnant colorectum after surgical resection of CRC. We evaluated the incidence of metachronous advanced neoplasia (AN) after surgery for CRC according to resection type and synchronous AN.
Methods:
This cohort study included patients who underwent surgical resection for initial CRC at a tertiary cancer center in Japan between September 2002 and December 2012. The cumulative probability of metachronous AN was calculated using the Kaplan-Meier method and was evaluated by the log-rank test.
Results:
Metachronous AN was detected in 145 of the 1731 included patients, and the 5-year cumulative probability of metachronous AN was 13.1%. There was no significant difference in the incidence of metachronous AN in the right-sided colorectal resection (RCR) versus left-sided colorectal resection (LCR) groups (log-rank test P = 0.151), whereas the incidence of metachronous AN was significantly higher in patients with synchronous AN (log-rank test P < 0.001). In subgroup analysis of patients according to resection type and synchronous AN, the LCR group with synchronous AN showed a significantly higher incidence of metachronous AN than the other groups (log-rank test P < 0.001).
Conclusions:
We found that synchronous AN, but not resection type, was independently associated with the incidence of metachronous AN in patients who underwent surgical resection of CRC. In addition, subjects with synchronous AN after LCR had a potentially increased risk for metachronous AN. Thus, it may be useful to perform risk stratification according to synchronous AN and resection type.
To investigate metachronous colorectal neoplasms among patients with no polyps, 519 patients in group A (62.5 ± 10.7 yr, M : F = 255 : 264) with negative colonoscopy at baseline, 495 in group B (65.2 ± 9.6 yr, M : F = 328 : 167) with diminutive polyps left untreated at baseline, and 581 in group C (mean age 65.0 ± 8.9 yr, M : F = 411 : 170) with colorectal adenoma more than 5 mm in size resected at baseline were colonoscopically followed up and their metachronous neoplasms were investigated (index lesion: high-grade adenoma or cancer, non-index lesion: low-grade adenoma). Median follow-up periods and frequencies of colonoscopy were 72.3, 61.6, and 61.9 months and 2.7, 3.4, and 3.6 times in groups A, B, and C. The cumulative incidences of metachronous non-index lesion and those of metachronous index lesion were 6.6%, 2.3% in group A, 14.7%, 5.1% in group B, and 24.1%, 7.2% in group C, respectively. The log-rank test revealed that the cumulative incidences of both non-index lesion and index lesion were lowest in group A with statistical significance as compared to those in group B (p < 0.0001, p < 0.005), and to those in group C (p < 0.0001, p < 0.0005). Persons with no polyps at baseline were considered to be at very low risk for advanced neoplasia within five years.
Background/aims:
Accurate in vivo differentiation of colon polyp histology may serve to prevent the resection of diminutive hyperplastic polyps in the distal colon or the need for histologic assesment of diminutive polyps after resection. The clinical implementation of these strategies depends on the prevalence of advanced histologic findings among diminutive polyps. We aimed to determine the prevalence of advanced histologic features (villous features, high-grade dysplasia, and adenocarcinoma) in diminutive colon polyps and compare it to small and larger polyps.
Patients/methods:
The data of patients who had undergone elective colonoscopy at a tertiary-care referral center were retrospectively reviewed. The size, morphology, and location of all polyps were recorded. Polyps were divided into 3 groups according to their size: diminutive (≤ 5 mm), small (6-9 mm), and large (≥ 10 mm).
Results:
A total of 7160 polyps in 3226 eligible patients were evaluated. The mean diameter of the polyps were 6.7 ± 4.9 mm. Histopathologic diagnosis were adenomatous in 4548 (63.5%) and non-adenomatous in 2612 (36.5%). Out of 7160 polyps, 4902 (68.5%) were diminutive (1-5 mm), 1360 (19%) were small (6-9 mm), and 898 (12.5%) large (≥ 10 mm) polyps. Among the diminutive polyps 2739 (55.9%) had adenomatous histology. There were 66 polyps (1.3%) with advanced histology in the diminutive group, 72 (5.2%) in the small group, 263 (29.2%) in the large polyp group. Diminutive polyps had a lower frequency of advanced histology compared to small and large polyps (p = 0.001). When the histology of the polyps were evaluated based on the size of the largest polyp the patient has, 2202 patients had polyp(s) ≤ 5 mm. The frequency of advanced histology was 2.2% in these patients.
Conclusions:
The prevalence of advanced histology in diminutive polyps is quite low (1.3%) which supports the clinical implementation of discard, resect and discard strategies in diminutive polyps.
Background:
In vivo prediction of colorectal polyp histology by narrow-band imaging (NBI) could potentially avoid post-polypectomy histologic examination or resection of diminutive lesions, thereby reducing costs and risk.
Objective:
To assess whether NBI is able to predict colonoscopy surveillance intervals and histology of distal diminutive polyps according to American Society for Gastrointestinal Endoscopy (ASGE) criteria.
Design:
Prospective, multicenter study.
Setting:
Five endoscopic centers.
Patients:
Consecutive patients undergoing colonoscopy in 5 centers were included.
Intervention:
Participating endoscopists were required to pass a before-study qualifying examination. Histology of polyps that were <10 mm was predicted at NBI and assigned a designation of high or low confidence.
Main outcome measurements:
Accuracy of high-confidence NBI prediction for polyps ≤5 mm in predicting surveillance intervals and negative predictive value (NPV) for adenomatous histology in the rectosigmoid colon were compared with the ASGE thresholds (90% agreement, 90% NPV).
Results:
A total of 278 patients (mean age, 63 years; 58% male) were enrolled. At colonoscopy, 574 (97.3%) polyps <10 mm (429 ≤5 mm, 60% adenomatous) were retrieved for histologic analysis. Sensitivity, specificity, positive and negative predictive values, and accuracy of high confidence-NBI predictions for adenomatous histology in lesions ≤5 mm were 90%, 88%, 89%, 89%, and 89%, respectively. High-confidence characterization of polyps ≤5 mm predicted the correct surveillance interval in 92% to 99% of cases, according to the American and European guidelines. NPV of high-confidence NBI for adenomatous histology for the rectosigmoid colon lesions ≤5 mm was 92%.
Limitations:
Only experienced endoscopists were included.
Conclusion:
High-confidence prediction of histology for polyps ≤5 mm appears to be sufficiently accurate to avoid post-polypectomy histologic examination of the resected lesions as well as to allow rectosigmoid hyperplastic polyps to be left in place without resection. (
Clinical trial registration number:
NCT01675752.).
Purpose
Many studies have reported on the use of narrow band imaging (NBI) colonoscopy to differentiate neoplastic from non-neoplastic colorectal polyps. It has potential to replace pathological diagnosis of diminutive polyps. We aimed to perform a systematic review and meta-analysis on the real-time diagnostic operating characteristics of NBI colonoscopy.
Methods
We searched PubMed, SCOPUS and Cochrane databases and abstracts. We used a two-level bivariate meta-analysis following a random effects model to summarise the data and fit hierarchical summary receiver-operating characteristic (HSROC) curves. The area under the HSROC curve serves as an indicator of the diagnostic test strength. We calculated summary sensitivity, specificity and negative predictive value (NPV). We assessed agreement of surveillance interval recommendations based on endoscopic diagnosis compared to pathology.
Results
For NBI diagnosis of colorectal polyps, the area under the HSROC curve was 0.92 (95% CI 0.90 to 0.94), based on 28 studies involving 6280 polyps in 4053 patients. The overall sensitivity was 91.0% (95% CI 87.6% to 93.5%) and specificity was 82.6% (95% CI 79.0% to 85.7%). In eight studies (n=2146 polyps) that used high-confidence diagnostic predictions, sensitivity was 93.8% and specificity was 83.3%. The NPVs exceeded 90% when 60% or less of all polyps were neoplastic. Surveillance intervals based on endoscopic diagnosis agreed with those based on pathology in 92.6% of patients (95% CI 87.9% to 96.3%).
Conclusions
NBI diagnosis of colorectal polyps is highly accurate—the area under the HSROC curve exceeds 0.90. High-confidence predictions provide >90% sensitivity and NPV. It shows high potential for real-time endoscopic diagnosis.
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.
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.
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).
The adenoma detection rate is an independent predictor of the risk of interval colorectal cancer after screening colonoscopy.
This document is the first update of the American College of Gastroenterology (ACG) colorectal cancer (CRC) screening recommendations since 2000. The CRC screening tests are now grouped into cancer prevention tests and cancer detection tests. Colonoscopy every 10 years, beginning at age 50, remains the preferred CRC screening strategy. It is recognized that colonoscopy is not available in every clinical setting because of economic limitations. It is also realized that not all eligible persons are willing to undergo colonoscopy for screening purposes. In these cases, patients should be offered an alternative CRC prevention test (flexible sigmoidoscopy every 5-10 years, or a computed tomography (CT) colonography every 5 years) or a cancer detection test (fecal immunochemical test for blood, FIT).
Discrimination between neoplastic and non-neoplastic lesions is crucial in colorectal cancer screening. Application of narrow-band imaging (NBI) in colonoscopy visualises mucosal vascular networks in neoplastic lesions and may improve diagnostic accuracy.
To compare the diagnostic efficacy of NBI in differentiating neoplastic from non-neoplastic colorectal lesions with diagnostic efficacies of standard modalities, conventional colonoscopy, and chromoendoscopy.
In this prospective study, 180 colorectal lesions from 133 patients were observed with conventional colonoscopy, and under low-magnification and high-magnification NBI and chromoendoscopy. Lesions were resected for histopathological analysis. Endoscopic images were stored electronically and randomly allocated to two readers for evaluation. Sensitivity, specificity and diagnostic accuracy of each endoscopic modality were assessed by reference to histopathology.
NBI and chromoendoscopy scored better under high magnification than under low magnification in comparison with conventional colonoscopy. The diagnostic accuracy of NBI with low or high magnification was significantly higher than that of conventional colonoscopy (low magnification: p = 0.0434 for reader 1 and p = 0.004 for reader 2; high magnification: p<0.001 for both readers) and was comparable to that of chromoendoscopy.
Both low-magnification and high-magnification NBI were capable of distinguishing neoplastic from non-neoplastic colorectal lesions; the diagnostic accuracy of NBI was better than that of conventional colonoscopy and equivalent to that of chromoendoscopy. The role of NBI in screening colonoscopy needs further evaluation.
To derive age and sex specific estimates of transition rates from advanced adenomas to colorectal cancer by combining data of a nationwide screening colonoscopy registry and national data on colorectal cancer (CRC) incidence.
Registry based study.
National screening colonoscopy programme in Germany.
Participants of screening colonoscopy in 2003 and 2004 (n = 840,149).
Advanced adenoma prevalence, colorectal cancer incidence, annual and 10 year cumulative risk of developing CRC among carriers of advanced adenomas according to sex and age (range 55-80+ years)
The age gradient is much stronger for CRC incidence than for advanced adenoma prevalence. As a result, projected annual transition rates from advanced adenomas to CRC strongly increase with age (from 2.6% in age group 55-59 years to 5.6% in age group >or=80 years among women, and from 2.6% in age group 55-59 years to 5.1% in age group >or=80 years among men). Projections of 10 year cumulative risk increase from 25.4% at age 55 years to 42.9% at age 80 years in women, and from 25.2% at age 55 years to 39.7% at age 80 years in men.
Advanced adenoma transition rates are similar in both sexes, but there is a strong age gradient for both sexes. Our estimates of transition rates in older age groups are in line with previous estimates derived from small case series in the pre-colonoscopy era independent of age. However, our projections for younger age groups are considerably lower. These findings may have important implications for the design of CRC screening programmes.
Objectives:
The adenoma detection rate (ADR) in screening colonoscopy is higher than original cost-effectiveness models estimated. Future colorectal cancer (CRC) risk is decreased once the ADR is 20%, but it is unclear how much additional protection is provided with higher ADRs. We modeled the impact of a high ADR on future CRC risk and surveillance colonoscopy burden.
Methods:
We created three hypothetical scenarios for 100,000 average-risk individuals undergoing screening colonoscopy at age 50: (i) 20% ADR with 30% future CRC risk reduction; (ii) 50% ADR with 30% future CRC risk reduction; and (iii) 50% ADR with 50% future CRC risk reduction. After colonoscopy, patients could have high-risk or low-risk adenomas, or no adenomas.
Results:
When the ADR increases from 20% to 50% but no additional CRC cases are prevented, future CRC risk for each group is still reduced, because lower-risk patients migrate into apparently higher-risk groups (the Will Rogers phenomenon). Future risk is further reduced if a 50% ADR leads to greater protection from CRC. However, despite the reductions in group-specific and overall future CRC risk, 34,635 additional surveillance colonoscopies are performed before the cohort is 60 years old when the ADR is 50% compared with 20%.
Conclusions:
If current surveillance practices continue along with high ADRs, screening colonoscopy may not remain cost-effective.
Background & aims:
Accurate optical analysis of colorectal polyps (optical biopsy) could prevent unnecessary polypectomies or allow a "resect and discard" strategy with surveillance intervals determined based on the results of the optical biopsy; this could be less expensive than histopathologic analysis of polyps. We prospectively evaluated real-time optical biopsy analysis of polyps with narrow band imaging (NBI) by community-based gastroenterologists.
Methods:
We first analyzed a computerized module to train gastroenterologists (N = 13) in optical biopsy skills using photographs of polyps. Then we evaluated a practice-based learning program for these gastroenterologists (n = 12) that included real-time optical analysis of polyps in vivo, comparison of optical biopsy predictions to histopathologic analysis, and ongoing feedback on performance.
Results:
Twelve of 13 subjects identified adenomas with >90% accuracy at the end of the computer study, and 3 of 12 subjects did so with accuracy ≥90% in the in vivo study. Learning curves showed considerable variation among batches of polyps. For diminutive rectosigmoid polyps assessed with high confidence at the end of the study, adenomas were identified with mean (95% confidence interval [CI]) accuracy, sensitivity, specificity, and negative predictive values of 81% (73%-89%), 85% (74%-96%), 78% (66%-92%), and 91% (86%-97%), respectively. The adjusted odds ratio for high confidence as a predictor of accuracy was 1.8 (95% CI, 1.3-2.5). The agreement between surveillance recommendations informed by high-confidence NBI analysis of diminutive polyps and results from histopathologic analysis of all polyps was 80% (95% CI, 77%-82%).
Conclusions:
In an evaluation of real-time optical biopsy analysis of polyps with NBI, only 25% of gastroenterologists assessed polyps with ≥90% accuracy. The negative predictive value for identification of adenomas, but not the surveillance interval agreement, met the American Society for Gastrointestinal Endoscopy-recommended thresholds for optical biopsy. Better results in community practice must be achieved before NBI-based optical biopsy methods can be used routinely to evaluate polyps; ClinicalTrials.gov number, NCT01638091.
When small colorectal lesions are accurately characterized, adenomas can be removed and discarded without formal histopathology analysis. Previous studies in an academic setting showed that many lesions can be managed accurately on the basis of their endoscopic image (optical diagnosis). We performed a prospective study to assess the accuracy of optical diagnosis of small colorectal polyps in a nonacademic setting (the DISCOUNT trial) by using high-resolution endoscopy (HRE) and narrow-band imaging (NBI).
During colonoscopy, 1 of 3 nonacademic endoscopists characterized small lesions and declared whether this was done with low or high confidence. In cases of high confidence, the endoscopists decided whether lesions should be removed and discarded or whether they could be left in situ. A surveillance interval was then recommended on-site.
Of 215 patients in the study, 108 were found to have 281 small lesions. Of these lesions, 231 were characterized with high confidence by using HRE or NBI; the level of corresponding sensitivity was 77.0% (95% confidence interval, 68.4-83.8), and specificity was 78.8% (95% confidence interval, 70.6-85.2). Of these lesions, 164 were assigned for removal, and 67 were assigned to remain in situ, including 9 adenomas. In 54 patients, a surveillance interval could be recommended on-site that was in line with Dutch guidelines for 44 patients.
Even though many lesions were characterized by HRE or NBI with high confidence, optical diagnosis in a nonacademic setting proved to be disappointing, with a sensitivity of 77.0% and a specificity of 78.8%. Many lesions were accurately assigned to be removed or remain in situ, although few adenomas were assigned to remain in situ. Also, 19% of on-site recommendations for a surveillance interval proved to be inaccurate.
A "resect and discard" policy has been proposed for diminutive polyps detected by screening colonoscopy, because hyperplastic and adenomatous polyps can be distinguished, in vivo, by using narrow-band imaging (NBI). We modeled the cost-effectiveness of this policy.
Markov modeling was used to compare the cost-effectiveness of universal pathology evaluations with a resect and discard policy for colonoscopy screening. In a resect and discard approach, diminutive lesions (≤5 mm), classified by endoscopy with high confidence, were not analyzed by a pathologist. Base case assumptions of an 84% rate of high-confidence classification, with a sensitivity and specificity for adenomas of 94% and 89%, respectively, were used. Census data were used to project outputs of the model onto the US population, assuming 23% as the current rate of adherence to a colonoscopy screening.
With universal referral of resected polyps to pathology, colonoscopy screening costs an estimated $3222/person, with a gain of 51 days/person. Endoscopic polypectomy accounted for $179/person, of which $46/person was related to pathology examination. Adoption of a resect and discard policy for eligible diminutive polyps resulted in a savings of $25/person, without any meaningful effect on screening efficacy. Projected onto the US population, this approach would result in an undiscounted annual savings of $33 million. In the sensitivity analysis, the rate of high-confidence diagnosis and the accuracy for endoscopic polyp determination were the most meaningful variables.
In a simulation model, a resect and discard strategy for diminutive polyps detected by screening colonoscopy resulted in a substantial economic benefit without an impact on efficacy.
Colonoscopy is used for early detection and prevention of colorectal cancer, but evidence on the magnitude of overall protection and protection according to anatomical site through colonoscopy performed in the community setting is sparse. We assessed whether receiving a colonoscopy in the preceding 10-year period, compared with no colonoscopy, was associated with prevalence of advanced colorectal neoplasms (defined as cancers or advanced adenomas) at various anatomical sites.
A statewide cross-sectional study was conducted among 3287 participants in screening colonoscopy between May 1, 2005, and December 31, 2007, from the state of Saarland in Germany who were aged 55 years or older. Prevalence of advanced colorectal neoplasms was ascertained by screening colonoscopy and histopathologic examination of any polyps excised. Previous colonoscopy history was obtained by standardized questionnaire, and its association with prevalence of advanced colorectal neoplasms was estimated, after adjustment for potential confounding factors by log-binomial regression.
Advanced colorectal neoplasms were detected in 308 (11.4%) of the 2701 participants with no previous colonoscopy compared with 36 (6.1%) of the 586 participants who had undergone colonoscopy within the preceding 10 years. After adjustment, overall and site-specific adjusted prevalence ratios for previous colonoscopy in the previous 10-year period were as follows: overall, 0.52 (95% confidence interval [CI] = 0.37 to 0.73); cecum and ascending colon, 0.99 (95% CI = 0.50 to 1.97); hepatic flexure and transverse colon, 1.21 (95% CI = 0.60 to 2.42); right-sided colon combined (cecum to transverse colon), 1.05 (95% CI = 0.63 to 1.76); splenic flexure and descending colon, 0.36 (95% CI = 0.16 to 0.82); sigmoid colon, 0.29 (95% CI = 0.16 to 0.53); rectum, 0.07 (95% CI = 0.02 to 0.40); left colon and rectum combined (splenic flexure to rectum, referred to as left-sided elsewhere), 0.33 (95% CI = 0.21 to 0.53).
Prevalence of left-sided advanced colorectal neoplasms, but not right-sided advanced neoplasms, was strongly reduced within a 10-year period after colonoscopy, even in the community setting.
Accurate optical diagnosis of small (<10 mm) colorectal polyps in vivo, without formal histopathology, could make colonoscopy more efficient and cost effective. The aim of this study was to assess whether optical diagnosis of small polyps is feasible and safe in routine clinical practice.
Consecutive patients with a positive faecal occult blood test or previous adenomas undergoing surveillance at St Mark's Hospital (London, UK), from June 19, 2008, to June 16, 2009, were included in this prospective study. Four colonoscopists with different levels of experience predicted polyp histology using optical diagnosis with high-definition white light, followed by narrow-band imaging without magnification and chromoendoscopy, as required. The primary outcome was accuracy of polyp characterisation using optical diagnosis compared with histopathology, the current gold standard. Accuracy of optical diagnosis to predict the next surveillance interval was also assessed and compared with surveillance intervals predicted by current guidelines using histopathology. This study is registered with ClinicalTrials.gov, NCT00888771.
363 polyps smaller than 10 mm were detected in 130 patients, of which 278 polyps had both optical and histopathological diagnosis. By histology, 198 of these polyps were adenomas and 80 were non-neoplastic lesions (of which 62 were hyperplastic). Optical diagnosis accurately diagnosed 186 of 198 adenomas (sensitivity 0.94; 95% CI 0.90-0.97) and 55 of 62 hyperplastic polyps (specificity 0.89; 0.78-0.95), with an overall accuracy of 241 of 260 (0.93, 0.89-0.96) for polyp characterisation. Using optical diagnosis alone, 82 of 130 patients could be given a surveillance interval immediately after colonoscopy, and the same interval was found after formal histopathology in 80 patients (98%) using British guidelines and in 78 patients (95%) using US multisociety guidelines.
For polyps less than 10 mm in size, in-vivo optical diagnosis seems to be an acceptable strategy to assess polyp histopathology and future surveillance intervals. Dispensing with formal histopathology for most small polyps found at colonoscopy could improve the efficiency of the procedure and lead to substantial savings in time and cost.
Leigh Family Trust, London, UK.
Standard white light colonoscopy has limited ability to differentiate between polyp types (adenomatous vs. hyperplastic). Narrow band imaging (NBI) highlights the superficial mucosal/vascular patterns on polyps and may facilitate real-time characterization of polyp histology. The aim of this study was to prospectively evaluate and compare the diagnostic characteristics of high-definition white light colonoscopy (HDWL) and NBI without magnification in the real-time prediction of polyp histology (adenomatous vs. hyperplastic) by evaluating the surface mucosal and vascular patterns.
We conducted a prospective comparative study in a tertiary referral center. A total of 100 patients referred for screening or surveillance colonoscopy were prospectively enrolled and underwent colonoscopy using a high-definition colonoscope with NBI capability. Every polyp detected was initially evaluated with HDWL followed by NBI for the presence of surface mucosal/vascular patterns. Based on these patterns, polyp histology was predicted by both modalities. The main outcome measurements were: (i) diagnostic characteristics of HDWL and NBI in predicting polyp histology and (ii) impact of polyp size and learning effect (first half of study vs. second half) on the ability of NBI to predict adenomas.
A total of 236 polyps were detected in 100 patients-143 adenomas, 77 hyperplastic, and 16 others. Surface patterns (type A: hyperplastic; type B: adenomatous) were recognized in all polyps with NBI (100%) compared to 45% with HDWL. For predicting adenomas, NBI had a significantly higher sensitivity and greater accuracy (96 and 93% respectively) compared with HDWL (38 and 61% respectively) (all P<0.0001). Although the accuracy of NBI for predicting adenomas improved with increasing polyp size (< or =5 mm; 6-9 mm; > or =10 mm) and in the second half compared with the first half of the study, these differences were not statistically significant.
Using a simple surface mucosal/vascular pattern classification, NBI without magnification was highly accurate and significantly superior to HDWL for the real-time prediction of adenomas.
Evidence from Japanese studies suggests that nonpolypoid colorectal neoplasia (NP-CRN) tends to be more pathologically advanced than polypoid neoplasia. However, data are limited regarding the prevalence of NP-CRN in an average-risk population. In addition, the diagnostic yield of the fecal occult blood test (FOBT) in relation to different types of colorectal neoplasms remains unclear. We prospectively investigated the prevalence and characteristics of polypoid and nonpolypoid colorectal lesions in an asymptomatic and average-risk Chinese population.
The study included 12,731 asymptomatic Chinese subjects (8372 of whom were average-risk subjects) who underwent screening colonoscopy. The prevalence, histopathologic findings, and topographic distribution of polypoid and nonpolypoid colorectal lesions were determined and analyzed. The diagnostic yield of FOBT, in relation to lesion morphology, also was assessed.
NP-CRN was detected in 552 (4.3%) asymptomatic and 348 (4.2%) average-risk subjects. The prevalence of depressed NP-CRN was 0.18% in both asymptomatic and average-risk subjects. A higher proportion of smaller-sized but high-grade dysplasia and invasive carcinoma beyond the submucosal layer was noted for depressed NP-CRN compared with flat NP-CRN or polypoid neoplasia. The diagnostic yield of FOBT was comparable in depressed lesions and their polypoid counterparts.
The prevalence of NP-CRN is substantial in both asymptomatic and average-risk Chinese individuals. Some subcategories of NP-CRN in this population tend to have more advanced pathologic characteristics. These findings may lead to modification of screening and prevention strategies for colorectal cancer.
Although microvascular vessels on the surface of colorectal polyps are observed by narrow-band imaging (NBI) with magnification, its clinical usefulness is still uncertain.
Our purpose was to evaluate the usefulness of meshed capillary (MC) vessels observed by NBI magnification for differentiating between nonneoplastic and neoplastic colorectal lesions.
Prospective polyp study.
National Cancer Center Hospital East, Chiba, Japan.
A total of 702 consecutive patients who underwent total colonoscopy between September and December 2004 were prospectively evaluated. Patients with polyps >10 mm and those with polyps previously evaluated by histologic examination or colonoscopy were excluded.
Lesions were classified into 2 groups: polyps with invisible or faintly visible MC vessels as nonneoplastic and polyps with clearly visible MC vessels as neoplastic. Lesions judged as nonneoplastic were subjected to biopsy and those as neoplastic were removed endoscopically. Histologic analysis was performed in all lesions.
Visible or invisible surface MC vessels, prediction of histologic diagnosis.
Of 92 eligible patients enrolled in this study, 150 lesions, including 39 (26%) hyperplastic polyps and 111 (74%) adenomatous polyps, were detected. Observation of MC vessels detected 107 of 111 neoplastic polyps and 36 of 39 nonneoplastic polyps. The overall diagnostic accuracy, sensitivity, and specificity were 95.3%, 96.4%, and 92.3%, respectively.
MC vessel judgment performed by a single colonoscopist with extensive experience in magnifying NBI.
Observation of surface MC vessels by magnifying NBI is a useful and simple method for differentiating colorectal nonneoplastic and neoplastic polyps.
Narrow band imaging (NBI) can accurately characterize colonic polyps using microvascular appearances. We aimed to assess whether the Kudo pit pattern classification is accurate when used with NBI (without dye-spray), and if microvascular appearances or NBI pit patterns maintain accuracy for polyp characterization at sizes < 10 mm.
116 polyps < 10 mm in size were detected in 62 patients undergoing surveillance colonoscopy. The polyps were prospectively assessed using NBI and magnification for Kudo pit pattern (III-V neoplastic, I-II non-neoplastic) and vascular pattern intensity (VPI), a measure of microvascular density (strong VPI, neoplastic; normal or weak VPI, non-neoplastic). Sensitivity, specificity, and accuracy were calculated and compared with results from histopathology.
The mean polyp size was 3.4 mm (range 1 - 9 mm). Overall, NBI pit pattern sensitivity, specificity, and accuracy were 0.88, 0.91, and 89.6 %, respectively. Equivalent values for VPI were 0.94, 0.89, and 91.4 %. Results were similar when polyps were subdivided into diminutive polyps (size <or= 5 mm) and flat polyps. Combining both pit pattern and VPI improved the sensitivity (0.98, P = 0.06 versus NBI pit pattern alone). There was very good agreement between NBI pit pattern and VPI for prediction of dysplasia (kappa = 0.83). No evidence of a learning curve for VPI was found. The NBI pit pattern was better than the VPI at subclassifying hyperplastic from other non-neoplastic polyps (sensitivity 0.79 versus 0.56, respectively, P = 0.02), but accuracy was poor.
The NBI pit pattern and VPI are both highly accurate in characterizing neoplastic colonic polyps of < 10 mm, with VPI appearing to be simple to learn. NBI has the potential to replace conventional histology for small polyps.
Colorectal cancer screening with diagnostic imaging can detect polyps. The management of patients whose largest polyp is less than 10 mm is uncertain. The primary aim of this study was to determine rates of advanced histology in patients undergoing colorectal cancer screening whose largest polyp is 9 mm or less.
Subjects include all asymptomatic adults receiving colonoscopy for screening during 2005 from 17 practice sites, which provide both colonoscopy and pathology reports to the Clinical Outcomes Research Initiative repository. Patients were classified by size of largest polyp. Advanced histology was defined as an adenoma with villous or serrated histology, high-grade dysplasia, or an invasive cancer. Risk factors for advanced histology were determined using Pearson chi(2) and Fisher exact tests.
Among 13,992 asymptomatic patients who had screening colonoscopy, 6360 patients (45%) had polyps, with complete histology available in 5977 (94%) patients. The proportion with advanced histology was 1.7% in the 1- to 5-mm group, 6.6% in the 6- to 9-mm group, 30.6% in the greater than 10-mm group, and 72.1% in the tumor group. Distal location was associated with advanced histology in the 6- to 9-mm group (P = .04) and in the greater than 10-mm group (P = .002).
One in 15 asymptomatic patients whose largest polyp is 6 to 9 mm will have advanced histology and would undergo surveillance at 3 years based on current guidelines. Because histology is necessary for this decision, most of these patients should be offered colonoscopy. Further study should determine whether patients whose largest polyp is 1-5 mm can be safely followed without polypectomy.
The natural history of untreated colonic polyps is uncertain. A retrospective review of Mayo Clinic records from a 6-yr period just before the advent of colonoscopy identified 226 patients with colonic polyps greater than or equal to 10 mm in diameter in whom periodic radiographic examination of the colon was elected over excisional therapy. In all patients, follow-up of polyps spanned at least 12 mo (mean, 68 mo; range, 12-229 mo) and included at least two barium enema examinations (mean, 5.2; range, 2-17). During the follow-up period, 83 polyps (37%) enlarged. Twenty-one invasive carcinomas were identified at the site of the index polyp at a mean follow-up of 108 mo (range, 24-225 mo). Actuarial analysis revealed that the cumulative risk of diagnosis of cancer at the polyp site at 5, 10, and 20 yr was 2.5%, 8%, and 24%, respectively. In addition, 11 invasive cancers were found at a site remote from the index polyp during the same follow-up period. These data further support the recommendation for excision of all colonic polyps greater than or equal to 10 mm in diameter. Periodic examination of the entire colon is recommended in this group of patients to identify neoplasms arising at a site remote from the index polyp. Although this study has limitations inherent to any retrospective analysis, comparable prospective data are unlikely to be available in the future because of the current widespread availability of colonoscopy.
We have updated guidelines for screening for colorectal cancer. The original guidelines were prepared by a panel convened by the U.S. Agency for Health Care Policy and Research and published in 1997 under the sponsorship of a consortium of gastroenterology societies. Since then, much has changed, both in the research rature and in the clinical context. The present report summarizes new developments in this field and suggests how they should change practice. As with the previous version, these guidelines offer screening options and encourage the physician and patient to decide together which is the best approach for them. The guidelines also take into account not only the effectiveness of screening but also the risks, inconvenience, and cost of the various approaches. These guidelines differ from those published in 1997 in several ways: we recommend against rehydrating fecal occult blood tests; the screening interval for double contrast barium enema has been shortened to 5 years; colonoscopy is the preferred test for the diagnostic investigation of patients with findings on screening and for screening patients with a family history of hereditary nonpolyposis colorectal cancer; recommendations for people with a family history of colorectal cancer make greater use of risk stratification; and guidelines for genetic testing are included. Guidelines for surveillance are also included. Follow-up of postpolypectomy patients relies now on colonoscopy, and the first follow-up examination has been lengthened from 3 to 5 years for low-risk patients. If this were adopted nationally, surveillance resources could be shifted to screening and diagnosis. Promising new screening tests (virtual colonoscopy and tests for altered DNA in stool) are in development but are not yet ready for use outside of research studies. Despite a consensus among expert groups on the effectiveness of screening for colorectal cancer, screening rates remain low. Improvement depends on changes in patients' attitudes, physicians' behaviors, insurance coverage, and the surveillance and reminder systems necessary to support screening programs.