- Colorectal cancer facts and figures: 2011–2013. American Cancer Society.http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-028323.pdf. Accessed October 25, 2011.
Previous estimates of the adenoma miss rate with optical colonoscopy (OC) are hindered by the use of OC as its own reference standard.
To evaluate the frequency and characteristics of colorectal neoplasms that are missed prospectively on OC by using virtual colonoscopy(VC) as a separate reference standard.DESIGN:
Prospective, multicenter screening trial.SETTING:
3 medical centers.
1233 asymptomatic adults who underwent same-day VC and OC.
Colorectal neoplasms (adenomatous polyps) missed at OC before VC results were unblinded.
Fourteen (93.3%) of 15 nonrectal neoplasms were located on a fold; 10 (71.4%) of these were located on the backside of a fold. Five (83.3%) of 6 rectal lesions were located within 10 cm of the anal verge.
Estimation of the OC miss rate depended on polyp detection on both VC and second-look OC and therefore underestimates the true OC miss rate, particularly for smaller polyps.
Most clinically significant adenomas missed prospectively on OC are located behind a fold or near the anal verge. The 12% OC miss rate for large adenomas ≥ 10 mm when state-of-the-art 3-dimensional VC is used as a separate reference standard is increased from the previous 0% to 6% estimates derived by using OC as its own reference standard.
Interval colorectal cancer (CRC) occasionally is detected in patients who have recently undergone colonoscopy. Systematic evaluation of CRC detected after colonoscopy could identify ways to improve the quality and the outcome of colonoscopy.
This study examined cancer diagnoses in the course of the dietary Polyp Prevention Trial, a randomized study of a dietary intervention on recurrence of adenomatous polyps. An algorithm was developed to classify each cancer into one of 4 etiologies: (1) incomplete removal (cancer at the site of previous adenoma), (2) failed biopsy detection (cancer in an area of suspected neoplasia with negative biopsy specimens), (3) missed cancer(large, advanced stage cancer found at a short interval after colonoscopy), or (4) new cancer (small, early stage cancer after a longer time interval).RESULTS:
Of 2079 patients, 13 had cancer detected over 5810 person years of observation (PYO) (2.2 cases/1000 PYO); 7/13 or 53.8% of patients had either a potentially “avoidable” cancer or one detectable at an earlier time interval because of incomplete removal (4/13) or missed cancer (3/13).
Interval cancer occurs despite colonoscopy. Improved quality of colonoscopy may have reduced cancer prevalence or resulted in earlier cancer detection in over 50% of prevalent cancers in the dietary Polyp Prevention Trial
- BACKGROUND & AIMS:
The miss rate of colonoscopy for neoplasms is poorly understood. The aim of this study was to determine the miss rate of colonoscopy by same day back-to-back colonoscopy.
Two consecutive same day colonoscopies were performed in 183 patients. The patients were randomized to undergo the second colonoscopy by the same or a different endoscopist and in the same or different positionRESULTS:
The overall miss rate for adenomas was 24%, 27% for adenomas <5 mm, 13% for adenomas 6-9 mm, and 6% for adenomas ≥ 1 cm. Patients with two or more adenomas at the first examination were more likely than patients with no or one adenoma detected at the first examination to have one or more adenomas at the second examination (odds ratio, 3.3; 95% confidence interval, 1.69-6.46). Right colon adenomas were missed more often (27%) than left colon adenomas (21%), but the difference was not significant. There was evidence of variation in sensitivity between endoscopists, but significant miss rates for small adenomas were found among essentially all endoscopists.CONCLUSIONS:
Using current colonoscopic technology, there are significant miss rates for adenomas < 1 cm even with meticulous colonoscopy. Miss rates are low for adenomas ≥ 1 cm. The results suggest the need for improvements in colonoscopic technology.
Although colonoscopy is currently the optimal method for detecting colorectal polyps, some are missed. The Third Eye Retroscope provides an additional retrograde view that may detect polyps behind folds.
To determine whether the addition of the Third Eye Retroscope to colonoscopy improves the adenoma detection rate.DESIGN:
Prospective, multicenter, randomized, controlled trial.
Nine European and U.S. centers.
Of 448 enrolled subjects, 395 had data for 2 procedures.
Subjects underwent same-day tandem examinations with standard colonoscopy (SC) and Third Eye colonoscopy (TEC). Subjects were randomized to SC followed by TEC or TEC followed by SC.
MAIN OUTCOME MEASUREMENTS:
Detection rates for all polyps and adenomas with each method.
In the per-protocol population, 173 subjects underwent SC and then TEC, and TEC yielded 78 additional polyps (48.8%), including 49 adenomas (45.8%). In 176 subjects undergoing TEC and then SC, SC yielded 31 additional polyps (19.0%), including 26 adenomas (22.6%). Net additional detection rates with TEC were 29.8% for polyps and 23.2% for adenomas. The relative risk of missing with SC compared with TEC was 2.56 for polyps (P < .001) and 1.92 for adenomas (P = .029). Mean withdrawal times for SC and TEC were 7.58 and 9.52 minutes, respectively (P < .001). The median difference in withdrawal times was 1 minute (P < .001). The mean total procedure times for SC and TEC were 16.97 and 20.87 minutes, respectively (P < .001).
Despite randomization and a large cohort, there was disparity in polyp prevalence between the 2 groups of subjects.
The Third Eye Retroscope increases adenoma detection rate by visualizing areas behind folds. (Clinical trial registration number: NCT01044732.).
Colonoscopy has been adopted as the preferred method to screen for colorectal neoplasia in the United States. However, lesions can be missed because of numerous factors, including location on the proximal aspect of folds or flexures, where they may be difficult to detect with the forward-viewing colonoscope. The Third Eye Retroscope (TER) is a disposable device that is passed through the instrument channel of a standard colonoscope to provide a retrograde view that complements the forward view of the colonoscope during withdrawal.
To evaluate whether experience with the TER affects polyp detection rates and procedure times in experienced endoscopists who had not previously used the equipment.
DESIGN, SETTING, PATIENTS:
This was an open-label, prospective, multicenter study at 9 U.S. sites, involving 298 patients presenting for colonoscopy, evaluating the use of the TER in combination with a standard colonoscope.
After cecal intubation, the 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:
Primary outcome measures were the number and size of adenomas and all polyps detected with the standard colonoscope and with the colonoscope combined with the TER. Secondary outcome measures were withdrawal phase time and total procedure time. Each endoscopist examined 20 subjects, divided into quartiles according to the order of their procedures, and results were compared among quartiles.
Overall, 182 polyps were detected with the colonoscope and 27 additional polyps with the TER, a 14.8% increase (P < .001). A total of 100 adenomas were detected with the colonoscope and 16 more with the TER, a 16.0% increase (P < .001). For procedures performed after each endoscopist had completed 15 procedures while using the TER, the mean additional detection rates with the TER were 17.0% for all polyps (P < .001) and 25.0% for adenomas (P < .001). For lesions 6 mm or larger, the overall additional detection rates with the TER for all polyps and for adenomas were 23.2% and 24.3%, respectively. For lesions 10 mm or larger, the overall additional detection rates with the TER for all polyps and for adenomas were 22.6% and 19.0%, respectively. The mean withdrawal times in the first and fourth quartiles were 10.6 and 9.2 minutes, respectively (P = .044).
There was no randomization or separate control group. The endoscopists judged whether each lesion could have been detected with the colonoscope alone by using their standard technique.
Polyp detection rates improved significantly with the TER, especially after 15 procedures, when the mean additional detection rate for adenomas was 25.0%. Additional detection rates with the TER for medium-size and large adenomas were greater than for smaller lesions. These results suggest that, compared with a colonoscope alone, a retrograde-viewing device can increase detection rates for clinically significant adenomas without detriment to procedure time or procedure complications. (Clinical trial registration number: NCT00969124.).
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.
To evaluate the added benefit for polyp detection during colonoscopy of a retrograde-viewing device.
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.
A total of 249 patients (age range 55-80 years) presenting for screening or surveillance colonoscopy.
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.
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.
There was no randomization or comparison with a separate control group..
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.).
- BACKGROUND AND STUDY AIMS:
Routine colorectal cancer screening, utilizing optical colonoscopy, has been shown to reduce the incidence and mortality rate of colorectal cancer. Despite its prevalence as the “gold standard” for neoplasia detection, the quality of colonoscopy screening is hindered by missed, undiagnosed lesions that may go undetected when located on the proximal aspect of haustral folds, rectal valves, the ileocecal valve, and/or flexures. The aim of this phase I feasibility trial is to assess the safety and efficacy of a new retrograde auxiliary imaging device, Third Eye Retroscope (Avantis Medical Systems, Inc., Sunnyvale, California, USA), used with optical colonoscopy to improve diagnostic yield.
PATIENTS AND METHODS:
A total of 29 consecutive patients were enrolled in this phase I single-institution prospective series. Primary efficacy endpoint was identification of polyps in the retrograde image that were not identified in the antegrade image during colonoscope withdrawal.
Of the 29 patients enrolled, 24 patients were treated and 34 out of a total of 38 polyps (classified as either adenoma or hyperplasia) were identified in the antegrade image. An additional four polyps, three hyperplastic and one adenoma, were identified in the retrograde image, and were detected on the proximal aspect of haustral folds during the colonoscope withdrawal, resulting in an 11.8% increase in diagnostic yield. No adverse events were encountered during the study.
A retrograde auxiliary imaging device used in conjunction with a standard optical colonoscope proved to be safe, technically feasible, and clinically promising. A phase II multi-institutional study is currently underway to further evaluate this device
Colonoscopy is the “gold standard” for colorectal polyp and cancer detection, but important lesions may be missed on the proximal aspect of haustral folds, rectal valves, or flexures.
Our purpose was to evaluate a prototype auxiliary imaging device that extends beyond the colonoscope’s tip, providing a continuous retrograde view to detect lesions missed by the forward-viewing colonoscope.
Three anatomic models of the colon were prepared with simulated polyps, 32% in obvious locations and 68% on the proximal aspect of folds. Six endoscopists examined each model with two methods. Method A used a standard video colonoscope. Method B involved an identical colonoscope with a retrograde-viewing auxiliary device positioned within its instrument channel. Order of testing was randomized and blinded.SETTING:
1233 asymptomatic adults who underwent same-day VC and OC.
MAIN OUTCOME MEASUREMENTS:
Detection rates for simulated polyps.
Of 78 “obvious” polyps, 69 (88%) and 70 (90%) were detected by methods A and B, respectively (P > .9). In contrast, of 162 polyps on proximal aspects of folds, 20 (12%) and 131 (81%) were detected by methods A and B, respectively (P < .00001).
Limitations resulted from (1) use of commercially available anatomic models in which haustral folds are less prominent and more rigid than in humans and (2) evaluation of a prototype device that had larger size and narrower angle of view than the planned production model and that was fixed in relation to the colonoscope.
In simulated testing, a retrograde-viewing auxiliary imaging device used with a standard video colonoscope significantly improvesdetection rates of simulated polyps and promises to enhance the diagnostic yield of colonoscopy in humans.
To determine which patients might benefit most from retrograde viewing during colonoscopy through subset analysis of randomized, controlled trial data.
The Third Eye® Retroscope® Randomized Clinical Evaluation (TERRACE) was a randomized, controlled, multicenter trial designed to evaluate the efficacy of a retrograde-viewing auxiliary imaging device that is used during colonoscopy to provide a second video image which allows viewing of areas on the proximal aspect of haustral folds and flexures that are difficult to see with the colonoscope’s forward view. We performed a post-hoc analysis of the TERRACE data to determine whether certain subsets of the patient population would gain more benefit than others from use of the device. Subjects were patients scheduled for colonoscopy for screening, surveillance or diagnostic workup, and each underwent same-day tandem examinations with standard colonoscopy (SC) and Third Eye colonoscopy (TEC), randomized to SC followed by TEC or vice versa.
Indication for colonoscopy was screening in 176/345 subjects (51.0%), surveillance after previous polypectomy in 87 (25.2%) and diagnostic workup in 82 (23.8%). In 4 subjects no indication was specified. Previously reported overall results had shown a net additional adenoma detection rate (ADR) with TEC of 23.2% compared to SC. Relative Risk (RR) of missing adenomas with SC vs TEC as the initial procedure was 1.92 (P = 0.029). Post-hoc subset analysis shows additional ADRs for TEC compared to SC were 4.4% for screening, 35.7% for surveillance, 55.4% for diagnostic and 40.7% for surveillance and diagnostic combined. The RR of missing adenomas with SC vs TEC was 1.11 (P = 0.815) for screening, 3.15 (P = 0.014) for surveillance, 8.64 (P = 0.039) for diagnostic and 3.34 (P = 0.003) for surveillance and diagnostic combined. Although a multivariate Poisson regression suggested gender as a possibly significant factor, subset analysis showed that the difference between genders was not statistically significant. Age, bowel prep quality and withdrawal time did not significantly affect the RR of missing adenomas with SC vs TEC. Mean sizes of adenomas detected with TEC and SC were similar at 0.59 cm and 0.56 cm, respectively (P = NS).
TEC allows detection of significantly more adenomas compared to SC in patients undergoing surveillance or diagnostic workup, but not in screening patients (ClinicalTrials.gov Identifier: NCT01044732).
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In the National Polyp Study (NPS), colorectal cancer was prevented by colonoscopic removal of adenomatous polyps. We evaluated the long-term effect of colonoscopic polypectomy in a study on mortality from colorectal cancer.
We included in this analysis all patients prospectively referred for initial colonoscopy (between 1980 and 1990) at NPS clinical centers who had polyps (adenomas and nonadenomas). The National Death Index was used to identify deaths and to determine the cause of death; follow-up time was as long as 23 years. Mortality from colorectal cancer among patients with adenomas removed was compared with the expected incidence-based mortality from colorectal cancer in the general population, as estimated from the Surveillance Epidemiology and End Results (SEER) Program, and with the observed mortality from colorectal cancer among patients with nonadenomatous polyps (internal control group)..
Among 2602 patients who had adenomas removed during participation in the study, after a median of 15.8 years, 1246 patients had died from any cause and 12 had died from colorectal cancer. Given an estimated 25.4 expected deaths from colorectal cancer in the general population, the standardized incidence-based mortality ratio was 0.47 (95% confidence interval [CI], 0.26 to 0.80) with colonoscopic polypectomy, suggesting a 53% reduction in mortality. Mortality from colorectal cancer was similar among patients with adenomas and those with nonadenomatous polyps during the first 10 years after polypectomy (relative risk, 1.2; 95% CI, 0.1 to 10.6).
These findings support the hypothesis that colonoscopic removal of adenomatous polyps prevents death from colorectal cancer. (Funded by the National Cancer Institute and others.)
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The Third Eye® Retroscope® auxiliary endoscopy system is intended for use in the instrument channel of a conventional colonoscope to provide retrograde illumination and visualization of the colon for diagnostic purposes.
CAUTION: Do not use this device for any purpose other than its intended use.
Preparation, recovery, and risks associated with a Third Eye colonoscopy are the same as for a standard colonoscopy procedure
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