Background: Analysis of exhaled breath, especially of volatile organic compounds (VOCs), is of increasing interest in the diagnosis of lung cancer. Compared with other methods of breath analysis, ion mobility spectrometry (IMS) offers a tenfold higher detection rate of VOCs. By coupling the ion mobility spectrometer with a multicapillary column as a pre-separation unit, IMS offers the advantage of an immediate twofold separation of VOCs with visualisation in a three-dimensional chromatogram. The total analysis time is about 500 s compared with gas chromatography/mass spectrometry (GC/MS) of about 1 h. It therefore seemed reasonable to test IMS in breath analysis.
Methods: In a pilot study, 32 patients with lung cancer were subjected to a breath analysis by IMS. Their IMS chromatograms were compared with those of 54 healthy controls. An IMS that was built for special clinical application was used to identify characteristic peaks of VOCs which might be relevant for the diagnosis of lung cancer in exhaled air of 10 ml volume.
Results: By a combination of 23 peak regions within the IMS chromatogram, patients with lung cancer, including a patient with carcinoma in situ, were classified and differentiated from healthy persons with an error rate of zero.
Conclusion: Breath analysis by IMS can detect a discriminating combination of VOCs in patients with lung cancer. By pattern recognition without the need for chemical analysis of the underlying VOCs, IMS has the potential to facilitate lung cancer diagnosis.