The contribution of endoscopy quality measures to the development of interval colorectal cancers in the screening population: a systematic review.

BACKGROUND: Colon cancer is the second most common cause of cancer-related death and an important cause of morbidity. The natural history of carcinogenesis, via the adenoma-carcinoma sequence, permits screening, which reduces the relative risk of mortality by up to 16%. The efficacy of a screening programme is limited by the growth of interval colorectal cancers between screening examinations. Quantifying the rate of interval cancers and delineating contributing endoscopic factors are crucial to maximise the benefit of a screening program.

METHODS: A systematic review was performed in accordance with PRISMA principles. Electronic databases were interrogated with a considered search strategy, and reference lists of retrieved papers were surveyed. For inclusion, studies included the rate of interval cancer (stated or calculated) and reported at least one of a predefined list of endoscopy characteristics. The primary outcome was to establish the rate of interval cancers. The secondary outcome was to determine the association between endoscopy quality measures and interval cancers.

RESULTS: The search yielded 2067 papers. Seventy-six full text papers were reviewed. Fifteen papers met the inclusion criteria. In total, there were 117,793 colon cancers, 7281 of which were interval lesions, giving an overall rate of 6.2%. The adenoma detection rate (ADR) of the endoscopist performing the index operation was the most consistent endoscopy factor associated with development of interval cancers. The impact of setting, volume and bowel preparation varied between papers.

CONCLUSION: Interval cancers reduce the efficacy of colorectal screening programmes. Ensuring the quality of the endoscopy process, specifically by increasing the ADR of practitioners, is crucial to the reduction of the rate of interval cancers.