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Previous research has found that adenoma detection rates (ADRs) and the characteristics of previously resected lesions are both associated with post-screening incidence of colorectal cancer (CRC) and mortality. However, their combined impact has remained unknown.

To remedy this knowledge gap, Monika Ferlitsch, MD, and Elisabeth Waldmann, MD, PhD, of the Medical University of Vienna, and colleagues used data from Austria's national quality assurance program for CRC screening colonoscopy to evaluate the combined effect of these two factors on incidence and mortality risk. They assessed almost 260,000 colonoscopies performed by 361 endoscopists and followed patients for as long as 12.2 years. Their results were recently published online in .

Ferlitsch and Waldmann outlined their key findings in the following interview with the Reading Room.

Have previous colonoscopy studies not shown that good ADRs are crucial to reducing CRC incidence and mortality?

Ferlitsch and Waldmann: Despite recent data showing very low long-term risk after colonoscopy, post-colonoscopy CRC and CRC-related deaths remain a problem after screening. The impacts of endoscopists' ADRs and lesion characteristics after adenoma removal have been well studied separately, but the combined effect of both factors on CRC-related mortality was unknown.

What were the main findings of your large population-based study and are they likely to impact the performance monitoring of endoscopists?

Ferlitsch and Waldmann: The present study found 165 CRC-related deaths during follow-up. Overall, CRC mortality after screening colonoscopy was very low, with a rate of less than 0.2% after 10 years. But individuals in all risk groups who were examined by a low-performing endoscopist with an ADR of less than 25% were at higher risk for CRC death than those examined by a high-performing endoscopist with an ADR of 25% or higher. High-quality colonoscopy was associated with a lower risk for CRC death in all risk groups, and this association was strongest for individuals with high-risk adenomas, who had a 40% lower risk for CRC death.

Individuals with high-risk adenomas require extensive surveillance and hence incur the most costs and utilize the most resources in healthcare systems.

What does this study add in terms of new evidence?

Ferlitsch and Waldmann: These findings add important new evidence on ways to reduce post-screening CRC mortality rates. The identification of the smallest possible group at the highest need for surveillance is crucial to save costs and resources, particularly with the COVID-19 pandemic's current drain on healthcare resources.

Do the findings differ substantially from those of earlier research?

Ferlitsch and Waldmann: Our findings are in line with those of earlier research, but show for the first time that considering ADR in combination with lesion characteristics would lead to further refinements in post-colonoscopy surveillance strategies.

Are any of the findings likely to be controversial in terms of mainstream thinking?

Ferlitsch and Waldmann: Individuals with high-risk adenomas are at significantly increased risk for CRC death if colonoscopy is done by a low-performing endoscopist. Hence, it is essential to stress that the performance quality of the index colonoscopy is crucial for correctly identifying the relatively small group of individuals in need of intensive surveillance.

How might the results alter the monitoring of colonoscopists' performance quality at colonoscopy centers?

Ferlitsch and Waldmann: These findings underline the importance of quality assurance monitoring, which is still often done on a voluntary basis. Given the impact of performance quality on CRC death, especially for individuals with high-risk polyps, we believe quality assessment for achieving required standards should be mandatory.

What's your final take-home message to gastroenterologists?

Ferlitsch and Waldmann: Combining the two factors of colonoscopy quality and adenoma characteristics can improve the risk stratification for CRC mortality in patients post-colonoscopy and help steward healthcare resources.

You can read the abstract of the study here, and about the clinical implications of the study here.