The Colorectal Breath Analysis (COBRA) Study

Colorectal cancer is the 2nd most common cause of cancer death in the UK where survival rates are among the lowest in Europe. If diagnosed early survival may exceed 90%. The proposed breath test is a non-invasive investigation that can detect the presence of volatile organic compounds (VOCs) in breath and their relative abundance in disease states including colorectal cancer. This test has potential to be used in a primary care setting to identify patients at high risk of colorectal cancer, supporting earlier referral for definitive investigation. A negative test may provide reassurance to patients and prevent unnecessary tests in this group. The test could also have an application for colorectal cancer screening. In this study the investigators will determine the diagnostic accuracy of an exhaled breath test for the detection of colorectal adenocarcinoma and colonic polyps. To determine the accuracy of the breath test a multicentre cross-sectional study will be conducted to analyse single breath samples from patients attending hospital for planned colonoscopy or elective resection of histologically confirmed colorectal cancer. The target for the study is 1463 patients. Breath collection will be conducted using a previously validated method. Samples of breath (500ml) collected using a CE-marked handheld ReCIVA sampling device (Owlstone Medical Ltd., Cambridge, UK) during a period of tidal breathing (approximately 5minutes) will be absorbed onto thermal desorption tubes (Markes International, Llantrisant, UK). All patients will have received bowel preparation and will be fasted for a minimum of 6 hours prior to the breath sample. Breath samples collected within thermal desorption tubes will be transferred to a central laboratory for analysis by gas chromatography mass spectrometry (GC-MS) and proton transfer reaction time of flight mass spectrometry (PTR-ToF-MS). Raw data files will be extracted and analysed in accordance with established protocols. Quality assurance measures will be formally assessed at each stage of sample handling.