Breath Analysis as an Additional Test for Colorectal Cancer Screening to Reduce the Number of Unnecessary Colonoscopies

Rationale: An electronic nose (eNose) is an artificial olfactory system that analyses volate organic compounds (VOCs) in exhaled breath. Exhaled human breath is mainly composed of inorganic compounds, inert gases and VOCs. VOCs are exhaled in very low concentrations and reflect pathological processes such as inflammation, oxidation, infection and neoplasms. The perspective is that metabolic and biochemical processes in several pathological situations cause different endogenous VOCs to arise, were they can serve as non-invasive biomarkers for certain diseases. Primary objective: To evaluate if the use of an additional breath test (AeonoseTM) for patients with a positive FIT-test can reduce the number of unnecessary colonoscopies. Secondary objectives: 1. External validation of results for CRC and (advanced) adenoma detection established in a previous studies (second study not yet published). (15) 2. To evaluate if VOC profiles in breath are similar at two different time points. 3. Acceptance rate of using the AeonoseTM device for VOC analysis in participating patients. Study population: Patients between the ages of 55 and 75 years old with a positive FIT-test referred for a colonoscopy procedure. Estimated sample size: 750 participants Intervention: Participants will be asked to breath through the AeonoseTM for 5 minutes during pre-colonoscopy intake and just prior to the procedure to assess reproducibility (with \>2 weeks in between). There are no risks, nor benefits for the participants.