Malignant pleural mesothelioma (MPM) is a rare and aggressive cancer caused by historical exposure to asbestos fibres. It is characterised by poor prognosis, mainly due to advanced stage diagnosis which limits curative treatment. Currently, MPM diagnosis is based on the histological assessment of pleural effusion fluids or lung biopsies. Such procedures are invasive, are often associated with comorbidity and limit the possibility of early diagnosis. Therefore, companion diagnostic biomarkers can massively improve the diagnostic process, especially when these biomarkers are able to detect MPM at an early stage. Several blood biomarkers, such as mesothelin and fibulin-3, have been investigated. However, they lack sensitivity and/or specificity, reducing their clinical utility as diagnostic tools and urging a continued search for new MPM biomarkers. To this end, we have created a non-invasive biomarker panel consisting of proteins in exhaled breath condensate (EBC). In the current project we aim to validate this panel.