Chest
Translating Basic Research Into Clinical PracticeBreathomics in Lung Disease
Section snippets
VOCs Reflect Metabolism in Humans
VOCs are gaseous organic molecules that are emitted from the fluid phase because they are highly volatile. Human VOCs are released from skin, with feces, urine, and breath and are derived from many metabolic pathways. Since cellular metabolism is altered by disease, the resulting change in VOCs may serve as biomarkers for particular pathophysiologic conditions. In pulmonary medicine, breath is of special interest because of its intensive contact with the respiratory tract. The rate at which
VOC Sampling and Handling
The potential to noninvasively sample breath VOCs is core to the attractiveness of these biomarkers. Depending on the specific application, a variety of techniques to collect exhaled breath are currently available. Progress is made in investigating the influence of these various techniques on exhaled VOCs to provide suggestions for standardization.11, 12, 13 Fortunately, the lack of international guidelines for sampling of VOCs is currently being addressed by task forces. An overview of the
VOC Analysis Techniques
The concepts of the analysis of volatile biomarkers can be understood best by discussing the two ends of the spectrum of available techniques (Fig 2). On one hand, these encompass chemical analytical techniques allowing identification of specific compounds. At the other end of the spectrum are pattern-recognition-based techniques allowing probabilistic dsicrimination of biomarker profiles. It is, however, important to realize that many techniques share features with both of these basic concepts.
Current State of VOC Research and Its Future Potential
The key opportunities and critical challenges for the application of VOCs in clinic are illustrated by the collective experience of their use in three diseases: lung cancer, respiratory infections, and obstructive lung disease.
Challenges and Future Directions
The potential benefits of VOC biomarkers are its noninvasiveness, speed, low costs, and applicability in low-income countries. Much work, however, is needed before VOC-based diagnostic tools meet the criteria in Table 1 and can be implemented, because current progress can only be classified as phase 2 to 4 on the 10-step technology readiness assessment scale.52
A key issue with volatile biomarkers identified to date is the relative absence of independently reproduced biomarkers undermining the
Acknowledgments
Financial/nonfinancial disclosures: The authors have reported to CHEST the following conflicts: Dr van Aalderen is a member of advisory boards for Astra Zeneca, Teva Pharmaceuticals Ltd, Mundipharma International, and AbbVie Inc. Drs van der Schee, Paff, Haarman, and Sterk and Mr Brinkman report no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
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Drs van der Schee and Paff are both first authors, contributing equally to this manuscript.
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