Breath analysis for the purpose of non-invasive diagnosis of
lung cancer has yielded numerous candidate compounds with still questionable clinical relevance. To arrive at suitable
volatile organic compounds our approach combined the analysis of different sources: isolated
tumor samples compared to healthy lung tissues, and exhaled breath from
lung cancer patients and healthy controls. Candidate compounds were further compared to substances previously identified in the comparison of transformed and normal lung epithelial cell lines. For human studies, a breath sampling device was developed enabling automated and CO2-controlled collection of the end-tidal air. All samples were first preconcentrated on multibed sorption tubes and analyzed with gas chromatography mass spectrometry (GC-MS). Significantly (p < 0.05) higher concentrations in all three types of
cancer samples studied were observed for
ethanol and
n-octane. Additional metabolites (inter alia 2-methylpentane,
n-hexane) significantly released by
lung cancer cells were observed at higher levels in
cancer lung tissues and breath samples (compared to respective healthy controls) with statistical significance (p < 0.05) only in breath samples. The results obtained confirmed the
cancer-related origin of volatile metabolites, e.g.
ethanol and
octane that were both detected at significantly (p < 0.05) elevated concentrations in all three kinds of
cancer samples studied. This work is an important step towards identification of volatile breath markers of
lung cancer through the demonstration of
cancer-related origin of certain volatile metabolites.