Exhaled breath condensate as a source of biomarkers for lung carcinomas. A focus on genetic and epigenetic markers-A mini-review.

Lung carcinoma is one of the most common causes of cancer-related mortality worldwide. It is an aggressive tumor, often diagnosed at an advanced stage when treatment options are limited. Currently, the importance of detection and assessment of various genetic alterations in cancer is recognized as they can serve as very helpful markers in early diagnosis and follow-up of treatment regimens. Recently, several therapeutically important genetic markers have been identified. One major problem is that tumor tissue specimens used to assay these genetic biomarkers are not always available, especially in the early stages of the disease. Therefore, exhaled breath condensates (EBC) could represent a good non-invasive source to allow the evaluation of these important genetic markers; these could help in the diagnosis, follow-up of the disease and/or assessment of treatment efficacy. The key aims of this review are first to describe the origin and constituents of EBC, as well as the different methodological procedures used in studying EBC biomarkers, and second, to document genetic and epigenetic markers that have been analyzed in EBC from lung cancer patients and to estimate their diagnostic and prognostic value.