In the clinical pathology labs, the most common biologic sample undergoing analysis is clearly blood/serum. Probably following this, in order of frequency, would be urine and cells, the latter in the form of Pap smears. The analysis of exhaled gases in the labs would be considered unusual although not uncommon in law enforcement by the use of the breathalyzer for measuring blood alcohol content. It make good intuitive sense that volatile substances in exhaled breath could be representative of lung cell metabolism and that malignant cells growing in the lung could display a different metabolic pattern than normal cells. Hence a diagnostic opportunity. A recent article raised the possibility that the analysis of exhaled breath would be useful to diagnose lung cancer (see: Breath gas aldehydes as biomarkers of lung cancer). Below is an excerpt from it, referring to a recent article by Fuchs et al. published in International Journal of Cancer:
There is experimental evidence that volatile substances in human breath can reflect presence of neoplasm. Lung cancer patients could be identified by means of exhaled pentanal, hexanal, octanal and nonanal concentrations. Exhaled aldehydes reflect aspects of oxidative stress and tumor-specific tissue composition and metabolism. Noninvasive recognition of lung malignancies may be realized if analytical skills, biochemical knowledge and medical expertise are combined into a joint effort.
Exhaled C1-C10 aldehydes could be detected in all healthy volunteers, smokers and lung cancer patients
Concentrations ranged from 7 pmol/l ...for butanal to 71 nmol/l...for formaldehyde
Exhaled pentanal, hexanal, octanal and nonanal concentrations were significantly higher in lung cancer patients than in smokers and healthy controls
Sensitivity and specificity of this method were comparable to the diagnostic certitude of conventional serum markers and CT imaging
Lung cancer patients could be identified by means of exhaled pentanal, hexanal, octanal and nonanal concentrations
Prior to reading this report, I had not considered the inclusion of chemicals in exhaled breath within the range of commonly used cancer biomarkers. Obviously, this is only an early experimental report but I suppose that it's possible that it could lead to a breathalyzer-like device for monitoring smokers for the presence of a malignant lung neoplasm. For any scientifically valid health screening test to achieve wide use, it either needs to be integrated into the public consciousness as essential, like mammography, or it needs to be convenient. A "cancer-Breathalyzer" would certainly fall into this second category if additional research proves it to be a valid diagnostic tool. From my perspective, the avoidance of a venepuncture takes the convenience factor of a "cancer-Breathalyzer" device to a whole new level.