Adenoma detection – the more the merrier?

The endoscopic detection and removal of adenomatous polyps plays a crucial role in the prevention of colorectal cancer (CRC). The efficiency of colonoscopy for CRC prevention relies first and foremost on the ability to detect adenomatous polyps. It is estimated that every 1 % increase in the adenoma detection rate (ADR) decreases the risk of post-colonoscopy cancer by 3 % [1] [2].

In this issue of Endoscopy, Williet et al. [3] present the results of a meta-analysis of 12 randomized controlled trials on the effect of Endocuff-assisted colonoscopy on adenoma detection rate. Endocuff (Norgine, Rueil Malmaison, France) is a cylindrical soft cuff that is attached to the tip of the colonoscope, and the authors found that the device flattened colonic folds and led to a significant increase in the ADR (41 % vs. 34 % when using standard colonoscopy). However, there are several factors that are interesting when we examine the study in more detail, and we may even ask whether increasing the ADR comes at a price.

Interestingly, the study did not demonstrate any increase in advanced adenoma detection rate, and the “better” ADRs for Endocuff were based on increased detection of low-risk adenomas. Progression of low-risk adenomas to CRC is slow or never happens for the majority of patients during their lifespan [4]. So, the effect on CRC prevention of devices that increase mainly detection of low-risk adenomas remains somewhat unclear. Further research in adequately powered studies is required to establish the effects on advanced adenoma detection of new modalities such as Endocuff. Moreover, the studies informing the meta-analysis lack uniform data reporting. Reported outcomes included ADR, advanced adenoma detection rate, ADR in the right-sided colon, and polyp detection rate, but a lack of consistency limits the capacity to draw conclusions on important aspects such as the ratio of increased polyp detection to diminutive vs. advanced adenoma detection.

“Surveillance colonoscopies, polypectomies, and histopathology evaluation might increase to a level where difference between performance optimization and potential overtreatment or overuse should be discussed.”

Although high adenoma detection has been shown to reduce post-colonoscopy CRC, an increased detection of low-risk adenomas will also translate into an increased use of surveillance colonoscopies. Most patients with such findings are currently scheduled to a 5-year surveillance interval according to the current US Preventive Services Task Force guidelines [5]. This 5-year interval is, in itself, questionable, as the protective effect of a high quality colonoscopy with complete clearance of only low-risk adenoma might actually extend up to 10 years or beyond [6] [7]. Furthermore, studies have shown that most clinicians tend to recommend shorter intervals for low- and intermediate-risk individuals than the intervals proposed by the guidelines [8], often recommending a 3-year interval instead of the suggested 5-year interval, even though no benefit is derived from such short intervals [9]. In this context, increasing polyp or adenoma detection might lead to large numbers of unnecessary colonoscopies. Significant costs are associated with such practice patterns, and the cost of pathology examinations furthermore reduces cost efficiency if the “resect and discard” or “diagnose and leave” strategies are not fully implemented in clinical practice [10] [11]. Surveillance colonoscopies, polypectomies, and histopathology evaluations might increase to a level where the difference between performance optimization and potential overtreatment or overuse should be discussed.

Pickhardt et al. demonstrated that when diminutive polyps are identified using computed tomography colonography, ignoring them is actually safe and cost-effective [12]. From an individual patient or endoscopist perspective, a higher ADR certainly seems “the merrier.” However, from the perspective of optimizing cost efficiency of population-based CRC screening programs, wise use of resources is needed. A recent study by Dubé et al. demonstrated that targeting colonoscopies toward unscreened individuals would be more beneficial in decreasing overall CRC incidence and mortality than surveillance of patients with low-risk adenomas [13]. As clinical resources are limited, such broader perspectives for optimal CRC prevention should be taken into account.

Although ADR remains our current gold standard for colonoscopy quality, future studies will have to establish adequate management and surveillance strategies for cohorts in which we achieve near-perfect adenoma detection.

• References

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