The following abstract from an Ehman et al. (2011) describes promising research that sniffing out volatile organic compounds (VOC) in human breath can be a tool for early cancer detection. Scientists are training dogs to do just that, breath analyses to detect metabolic disorders, amongst them cancer (Seyfried & Shelton, 2010).
I found a paper by an Austro-Polish research team as an excellent starting point in the realm of breath analyses to serve as a biomarker for disease. The paper is titled “Human exhaled air analytics: biomarkers of disease.” In it Buszewski, Kęsy, Ligor, & Amann (2007) elaborate on the chemistry of VOCs, first discovered by Linus Pauling in the ‘70s.
Looking to human breath to detect disease is nothing new and dates back to the very early history of medicine. A perfect example is the smell of acetone in uncontrolled diabetes (Buszewski et al., 2007).
Back to cancer and breath analyses. Here is the abstract from Ehman et al. (2011).