VOCs and Breath
There are many challenges associated with cancer management, including delayed diagnosis, low efficacy of treatment, and heterogeneity of disease. CT, MRI, and PET scans cannot identify small tumours, meaning it is difficult to achieve early diagnosis for patients. Histological biopsy is considered the gold standard for cancer diagnosis; however, it is invasive, time-consuming, and expensive. There is an urgent need for low cost and accessible diagnostic techniques that would allow for the earlier detection of cancer, personalised therapy, and assessment of treatment efficacy.
Volatile organic compounds (VOCs) are gaseous compounds produced throughout the body by numerous biological processes and released in biological samples such as faeces, urine, blood, and breath, with many advantageous attributes that position them as candidate novel biomarkers for cancer. The VOCs detectable in the breath can originate either from within the body (endogenous VOCs) or from external sources such as diet, medication, and environmental exposure (exogenous VOCs). Endogenous VOCs are produced throughout the body, Figure 1. Pathways of volatile organic compounds (VOCs) from exogenous (environmental and microbial) and endogenous (metabolic, degradation, and immune response) sources to exhaled breath picked up, and distributed via the bloodstream, before being exhaled in breath (Figure 1). Exogenous VOCs interact with biological systems and provide valuable health and disease information. The collection, identification, and quantification of these VOCs can provide a window into what is happening inside the body, offering great potential as non-invasive biomarkers to indicate disease onset and progression.
Exhaled breath, enriched with VOCs, offers a promising sample matrix for clinical analysis and diagnosis of disease. By testing breath samples against established reference ranges, clinicians in the future could detect abnormal VOC levels that may signal the presence of disease. Compared to traditional sampling methods such as blood and faeces, breath analysis provides several key benefits; primarily its non-invasiveness, enhancing patient comfort and simplifying the approval process for clinical trials. Breath is an abundant and renewable resource, allowing for preconcentration of its compounds before analysis, which can improve test accuracy. Another important advantage is the flexibility of breath sampling, which can be conducted virtually anywhere. This opens the door to decentralised trial designs and at-home testing, making disease monitoring and diagnosis more accessible and convenient for patients.
