Making colonoscopy-based screening more efficient: a ‘gateopener’ approach

Abstract Objectives To assess the potential of an innovative approach to colonoscopy-based screening for colorectal cancer (CRC), by use of a single, low threshold fecal immunochemical test (FIT) as a ‘gateopener’ for screening colonoscopy. Design Simulation study using COSIMO, a validated Markov-based simulation model, in a hypothetical German population. Setting Modelled scenarios included either direct invitation to screening colonoscopy or mailing a single (‘gateopener’) FIT along with an invitation to colonoscopy contingent on a FIT value above a low threshold yielding a 50% positivity rate (i.e., every other pre-test will be positive). The main analyses focused on scenarios assuming identical colonoscopy uptake, resulting from higher adherence to the gateopener FIT than to primary use of colonoscopy and avoidance of colonoscopy in those with below-threshold FIT values. Participants Hypothetical cohorts of 100,000 previously unscreened men and women using screening at different ages and with varying levels of adherence. Interventions Screening colonoscopy without and with preceding gateopener FIT. Main outcome measure Detected and prevented CRC cases and deaths within 10 years. Results Across all ages and both sexes, use of screening colonoscopy contingent on a positive gateopener FIT yielded approximately doubled cancer detection rates as compared to conventional screening. In those spared from undergoing screening colonoscopy due to a negative FIT pretest, numbers needed to screen were 10-times higher as compared to those for individuals with a positive FIT, peaking in more than 2500 and more than 3800 (hypothetically) needed colonoscopies to detect one case of cancer in 50-year-old men and women, respectively. At identical levels of colonoscopy use, gateopener screening resulted in 51-53% and 63-68% more prevented CRC cases and deaths, respectively. Conclusions By directing colonoscopy capacities to those most likely to benefit from it, offer of screening colonoscopy contingent on a ‘gateopener’ low-threshold FIT would substantially enhance efficiency of colonoscopy screening. Summary Box What is already known on this topic Screening colonoscopy as primary examination is inefficient as most of the screened subjects would never develop colorectal cancer even without screening. Efficiency could be enhanced by pre-selecting those most likely to benefit, e.g., by use of a single low-threshold faecal immunochemical test (‘gateopener’ FIT) What this study adds A simulation where only individuals with positive gateopener FIT proceeded to screening colonoscopy resulted in 50% fewer colonoscopies required to detect one case of cancer vs conventional screening colonoscopy. At identical colonoscopy uptake rates, the gateopener approach implied approximately 50% and 70% more prevented colorectal cancer cases and deaths, respectively. Inviting subjects to undergo pre-testing with low-threshold FITs would markedly improve efficiency of colonoscopy-based screening.