An efficient strategy for evaluating new non-invasive screening tests for colorectal cancer: the guiding principles

Objective: New screening tests for colorectal cancer (CRC) are rapidly emerging. Conducting trials with mortality reduction as the end point supporting their adoption is challenging. We re-examined the principles underlying evaluation of new non-invasive tests in view of technological developments and identification of new biomarkers. Design: A formal consensus approach involving a multidisciplinary expert panel revised eight previously established principles. Results: Twelve newly stated principles emerged. Effectiveness of a new test can be evaluated by comparison with a proven comparator non-invasive test. The faecal immunochemical test is now considered the appropriate comparator, while colonoscopy remains the diagnostic standard. For a new test to be able to meet differing screening goals and regulatory requirements, flexibility to adjust its positivity threshold is desirable. A rigorous and efficient four-phased approach is proposed, commencing with small studies assessing the test’s ability to discriminate between CRC and non-cancer states (phase I), followed by prospective estimation of accuracy across the continuum of neoplastic lesions in neoplasia-enriched populations (phase II). If these show promise, a provisional test positivity threshold is set before evaluation in typical screening populations. Phase III prospective studies determine single round intention-to-screen programme outcomes and confirm the test positivity threshold. Phase IV studies involve evaluation over repeated screening rounds with monitoring for missed lesions. Phases III and IV findings will provide the real-world data required to model test impact on CRC mortality and incidence. Conclusion: New non-invasive tests can be efficiently evaluated by a rigorous phased comparative approach, generating data from unbiased populations that inform predictions of their health impact

Most Premature Surveillance Colonoscopy Is Not Attributable to Bowel Preparation or New Clinical Indications

Surveillance colonoscopy frequently occurs prior to recommended intervals. Studies delineating the reasons why premature surveillance occurs are limited. We sought to define the frequency in which premature surveillance colonoscopy occurs in the setting of an inadequate bowel preparation or with a provided patient clinical indication versus when premature surveillance colonoscopy occurs without any provided discernible rationale in the setting of adequate bowel preparation. A retrospective cross-sectional cohort study of 700 patients undergoing colonoscopy for an indication of "surveillance of polyps" from 2008 to 2014 at two tertiary-care referral centers was carried out. Patients were deemed either "adherent" or "premature" based on US Multi-Society Task Force guideline intervals for surveillance colonoscopy. A documented decision-making rationale for premature surveillance was determined through review of the electronic medical record with assessment of clinical notes and endoscopy order and report. Premature surveillance occurred in 43.0 % (n = 301) of all surveillance colonoscopies performed. Among the premature cases, rationale was attributed to inadequate bowel preparation in 17.3 % (n = 52) and due to a new clinical indication in 21.6 % (n = 65). Most commonly, in 61.1 % (n = 184) of premature cases, no rationale was documented for the early colonoscopy. Documented decision-making rationale for premature surveillance colonoscopy is usually absent in premature cases with inadequate bowel preparation and new clinical indications explaining only a minority of the occurrences

Metachronous Advanced Neoplasia on Surveillance Colonoscopy in Patients With Young- vs Older-onset of Colorectal Cancer

The incidence of colorectal cancer (CRC) and cancer-related mortality has increased in patients <55 years old.1 Consensus on optimal intervals for post-CRC surveillance colonoscopy in young patients is lacking. The primary endpoint of this study was comparison of rates of metachronous advanced neoplasia (AN) in patients diagnosed with CRC at <50 and 50–75 years. The secondary aim was to evaluate risk factors of metachronous AN