VOCs vs FIT for Colorectal Cancer Screening

Endogenous breath VOCs (Volatile Organic Compounds) are present in various excreted biological materials (urine, blood, faeces an breath) and their analysis offers a possibility for cancer screening. Some of these VOCs are reversed in the venous blood stream and reach the lung alveoli where some of them are exhaled. Colorectal cancer (CRC) is one of the commonest tumours and is an important cause of cancer-related mortality. Colonoscopy is the gold standard for the diagnosis of CRC. Screening with fecal immunochemical test (FIT) is associated with a 13-18% CRC-mortality reduction. Aim of the study To compare the reliability of this breath analysis with Immunochemically-based Fecal Occult Blood Test.

Volatile organic compounds (VOCs) are low molecular weight (<1 kDa) compounds which represent the final products of cell metabolism. Their composition can be affected by several factors including diet, hormones, environment and the presence of diseases, in particular, cancer. Endogenous breath VOCs are present in various excreted biological materials (urine, blood, faeces an breath) and their analysis offers a possibility for cancer screening. Some of these VOCs are reversed in the venous blood stream and reach the lung alveoli where some of them are exhaled. Colorectal cancer (CRC) is one of the commonest tumours and is an important cause of cancer-related mortality. Colonoscopy is the gold standard for the diagnosis of CRC, although its cost prevents its use for mass screening. Furthermore colonoscopy is not well accepted by patients since it is an invasive exam. Screening with fecal immunochemical test (FIT) is associated with a 13-18% CRC-mortality reduction in major randomized studies and is the most widely used non-invasive screening tool, showing fairly good specificity but a high variation in sensitivity (61-91%) and adherence to screening programmes rarely reaches 50-70% of the target population. Recently the breath analysis has been demonstrated to be a new well accepted and non-invasive tool to detect colorectal cancer. The purpose of this trial is to compare the reliability of this breath analysis with Immunochemically-based Fecal Occult Blood Test, which is the routinely employed tool for mass screening. A group of subjects adherent to the regional screening program for colorectal cancer prevention, who resulted positive to the FIT, will be enrolled in this study, and will have a breath sampling before undergoing colonoscopy. The predictive ability of the Breath test will be tested in a blind fashion in this selected group of high-risk subjects.

The breath of all patients with positive FIT (fecal immunochemical test) but negative colonoscopy will be sampled using a breath sampler

The breath of all patients with positive FIT (fecal immunochemical test) and a colorectal cancer detected by colonoscopy will be sampled using a breath sampler

The breath of all patients with positive FIT (fecal immunochemical test) and a colonic polyp detected by colonoscopy will be sampled using a breath sampler

The breath of all subjects included will be sampled using a device able to capture the alveolar air and to fix it on carbon tubes, Then the tubes will be desorbed and analysed using gas chromatography

Inclusion Criteria: Patients with and without positive FIT with a planned colonoscopy Patients included in the regional screening program for CRC Written informed consent Exclusion Criteria: Pregnancy Inflammatory bowel disease Bowel prep Any psychiatric disease Previous (or still present) cancers in other organs

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