Colonoscopic adenoma detection – new super wide-angle scopes versus new caps

Thomas Rösch, Hamburg and Jens Aschenbeck, Berlin

Gut. 2016 Aug 9. pii: gutjnl-2016-311906

Objective

Miss rate of polyps has been shown to be substantially lower with full-spectrum en-doscopy (FUSE) compared with standard forward-viewing (SFV) colonoscopy in a tan-dem study at per polyp analysis. However, there is uncertainty on whether FUSE is also associated with a higher detection rate of colorectal neoplasia, especially advan-ced lesions, in per patient analysis.

Methods

Consecutive subjects undergoing colonoscopy following a positive faecal immuno-chemical test (FIT) by experienced endoscopists and performed in the context of a re-gional colorectal cancer population-screening programme were randomised between colonoscopy with either FUSE or SFV colonoscopy in seven Italian centres. Randomi-sation was stratified by gender, age group and screening history. Primary outcomes included detection rates of advanced adenomas (A-ADR), adenomas (ADR) and sessi-le-serrated polyps (SSPDR).

Results

Of 741 eligible subjects, 658 were randomised to either FUSE (n=328) or SFV (n=330) colonoscopy and included in the analysis. Overall, 293/658 and 143/658 subjects had at least one adenoma (ADR 44.5%) and advanced adenoma (A-ADR 21.7%), re-spectively, while SSP was the most advanced lesion in 18 cases (SSPDR 2.7%). ADR and A-ADR were 43.6% and 19.5% in the FUSE arm, and 45.5% and 23.9% in the SFV arm, with no difference for both ADR (OR for FUSE: 0.96, 95% CI 0.81 to 1.14) and A-ADR (OR for FUSE: 0.82, 95% CI 0.61 to 1.09). No difference in SSPDR or multipli-city was detected between the two arms. In the per polyp analysis, the mean number of adenomas and proximal adenomas per patient was 0.81±1.25 and 0.47±0.93 in the FUSE arm, and 0.85±1.33 and 0.48 ±0.96 in the SFV colonoscopy arm (p=NS for both comparisons).

Conclusions

No statistically significant difference in ADR and A-ADR between FUSE and SFV colo-noscopy was detected in a per patient analysis in FIT-positive patients.

Gut. 2015 Dec 16. pii: gutjnl-2015-310097

Background and aims

Colonoscopy is the current reference standard for the detection of colorectal neopla-sia, but nevertheless adenomas remain undetected. The Endocuff, an endoscopic cap with plastic projections, may improve colonic visualisation and adenoma detection. The aim of this study was to compare the mean number of adenomas per patient (MAP) and the adenoma detection rate (ADR) between Endocuff-assisted colonoscopy (EAC) and conventional colonoscopy (CC).

Methods

We performed a multicentre, randomised controlled trial in five hospitals and included fecal immonochemical test (FIT)-positive screening participants as well as sympto-matic patients (>45 years). Consenting patients were randomised 1:1 to EAC or CC. All colonoscopies were performed by experienced colonoscopists (≥500 colonoscopies) who were trained in EAC. All colonoscopy quality indicators were prospectively recorded.

Findings

Of the 1063 included patients (52% male, median age 65 years), 530 were allocated to EAC and 533 to CC. More adenomas were detected with EAC, 722 vs 621, but the gain in MAP was not significant: on average 1.36 per patient in the EAC group versus 1.17 in the CC group ( p=0.08). In a per-protocol analysis, the gain was 1.44 vs 1.19 (p=0.02), respectively. In the EAC group, 275 patients (52%) had one or more adenomas detected versus 278 in the CC group (52%; p=0.92). For advanced adenomas these numbers were 109 (21%) vs 117 (22%). The adjusted caecal intubation rate was lower with EAC (94% vs 99%; p<0.001), however when allowing crossover from EAC to CC, they were similar in both groups (98% vs 99%; p value=0.25).

Interpretation

Though more adenomas are detected with EAC, the routine use of Endocuff does not translate in a higher number of patients with one or more adenomas detected. Whether increased detection ultimately results in a lower rate of interval carcinomas is not yet known.

What you should know about these papers

Adenoma detection rate (ADR) has become the holy grail of colonoscopy outcome quality measurement and efforts to increase ADR are ongoing. The relevance of ADR as surrogate parameter of outcome quality is backed up by data showing correlations of ADR in interval cancers ^1-3. Although the relevance of small adenomas is unknown or even doubted⁴, and increases in ADR in screening programmes have often been caused mainly by increased detection of such small ademomas⁵, efforts to increase ADR by different technical modifications of colonoscopy are multiple using different approaches⁶. Among those, image processing (NBI/narrow band imaging, i-Scan, FICE) and red flag techniques (autofluorescence) as well as widening the colonoscopic view and mechanical methods (caps, balloons), most of them without great success. Neither HDTV imaging⁷ nor NBI and similar techniques from different companies^8-10 nor autofluorescence endoscopy as the only red flag technique evaluated in several clinical trials¹¹ have not shown to consistently increase ADR. Normal transparent caps have not been successful either, although here the data were more conflicting^{10, 12}. Wide angle colonoscopy (increases from 140° to 170°) were not successful either¹³. There are two new kids on the block: Super-wide angle colonoscopies and new caps. The former increase the angle of view to 330° using the so-called FUSE colonoscopy or instruments from other companies. An initial study was very promising, showing greatly reduced adenoma miss rates. This tandem study in 185 patients had adenoma miss rates of 7% for the FUSE scope versus 41% for the conventional colonoscopies of different companies, mostly not of the latest generation¹⁴. Usually, studies of that kind should be reproduced by other groups. The new study on the FUSE colonoscope came from the Italian FIT-based colorectal cancer screening programme, used a simple comparison instead of a tandem design and did not show any difference in any of the parameters. 658 patients were randomized to either FUSE or conventional colonoscopy, again mostly not of the latest generation¹⁵. ADR was 44.5% in the entire study, without any differences between the two groups (43.6% FUSE vs. 45.5% control), as were the rates of advanced adenomas (19.5% vs 23.5%). Similarly, rates of small and large adenomas and of sessile serrated polyps were also the same. How can this be explained ? First of all the tandem design is in my opinion an interesting methodology and requires less patient numbers, but does not reflect daily practice (patients undergoing only one colonoscopy) and is perhaps more prone to bias, since examiners care may be different depending on their willingness to find more lesions with one scope or the other (it can be discussed whether the same bias would apply to simple comparative randomized trials). Furthermore, the setting (screening vs. diagnostic) and the overall ADR may be different, although not so much in the two studies here^{14, 15}. In addition, studies using super-wide angle scopes did not suggest that ADR would be dramatically increased¹⁶. Finally, positive results are more credible if confirmed by several studies. The other candidate is the endocuff a cap with small soft lateral rubber arms arranged in two, or more recently, one rings around the cap (Endocuff Vision) in order to avert and flatten folds on colonoscope withdrawal. Initial studies were promising, but the ADR in the control group was rather low. In two subsequent very similar studies with about 500 patients each from the same group, ADR was 36%¹⁷ and 35.4%¹⁸ for endocuff colonoscopy, but decreased in the control group from 28%¹⁷ in the first to 20.7%¹⁸ in the second. Could these results be confirmed ? Partially with a marginal benefit by a large subsequent study from the Netherlands and fully (higher ADR) by an even larger UK trial presented at UEGW. Both were performed in mixed collectives (screening, surveillance and diagnostic). In the Dutch study only the number of adenomas, but not the adenoma detection rates which were rather high. The study included 1063 patients, and ADR was 52% in both in the per-protocol analysis, but not in the overall analysis (1.36 vs. 1.17). Advanced adenomas and sessile serrated lesions were exactly the same, but small adenomas < 6 mm and flat adenomas were more frequently detected in the endocuff group¹⁹. Finally, the recent very large UK study (n=1772) again showed superiority of endocuff, this time with the second generation (Endocuff Vision), in achieving again a higher ADR, namely 40.9% vs 36.2% in the control arm²⁰. Here, subgroup analysis showed significant differences in favour of endocuff vision for left sided adenomas (26.1% vs 22.2%), small adenomas < 10 mm, sessile serrated adenomas – and surprisingly even in cancers (4.1% vs 2.3%), a bit hard to believe. Thus, it seems that mechanical methods flattening the inner colonic surface are superior to increasing the endoscopic angle of view – and they are simpler. The next device, a balloon, as already around the corner. The so-called G-eye consists of a balloon mounted around the endoscope tip (of any colonoscope) which stays there permanently for a large number of examinations and is reprocessed with the scope. A multinational group published dramatically reduced miss rates in a small tandem study (n=126), namely from 44.7% with conventional scopes to 7.5% with a balloon around the endoscope tip (G scope)²¹. The same group has now presented a large randomized multicenter study at UEGW, in which 13 hospitals included 408 patients (mixed hospital collective, simple comparison) in the published abstract22 and 1000 in the oral presentation with dramatic differences in ADR including all subgroups: In the abstract, ADR was 49.2% vs. 33.8%, accounting for a 45.6% increase; increases were even more dramatic for almost all subgroups (96% increase of large and advanced adenomas by G-eye²²). In the oral presentation, flat adenomas and sessile serrated adenomas (SSA) in the right colon were increased by 160% and 550%, respectively, in figures flat adenomas 62 vs 24 and right-sided SSA 13 vs 2 – not very many for 1000 cases anyway. In view of the most dramatic increase of ADR by any method shown by any group in recent years we are glad to await confirmatory results by other groups, e.g. in a pure screening setting.

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