Breath analysis for the non-invasive assessment of colorectal cancer

Abstract

Colorectal cancer (CRC) is one of the leading malignancies worldwide and the early diagnosis of CRC is the key to better prognosis. Breath analysis which lacks standardization is a novel method potentially capable of non-invasive CRC detection and monitoring. The objective was to develop a VOC base model for diagnosis and monitoring of CRC. Secondary aims were to explore the different methodology including the influence of off-line sampling, perform multiplatform correlation of VOCs in human breath. Initial studies determined the strengths and weaknesses of three different breath sampling devices. Findings showed that no single device has all the desired attributes of optimal method for breath collection system. The device chosen for future clinical studies because of the acceptable VOC capture, repeatability, and human factor analysis. A study of the comparability of the different VOC analytical methods were done to confirm the possibility of cross validating the VOCs. The results supported the implementation of an off- line thermal desorption-based platform for breath collection in multi-site studies for breath biomarker research. Analysis of room air VOCs provide baseline understanding of their ambient levels and potential contribution as contaminants. The background noise could be mostly ignored with a single background sample analysis. Adapting these methods VOCs levels were examined in the tumour headspace and exhaled breath of patients with colorectal cancer. Tumour headspace analysis showed tumour and colonic mucosa might release different VOC which is detectable on mass spectrometry. Exhaled breath from CRC patients provided tentative evidence that selected exhaled VOCs were linked to CRC and that the compounds may change as a response to therapeutic intervention and disease status. Further work is however, needed to refine the methodology for sample collection and handling to ensure reliability of results.