Stockhammer P, Ploenes T, Theegarten D, et al. - Corresponding pleural effusions and serum samples collected at primary diagnosis were assessed for transforming growth factor-beta (TGF-β) by ELISA, and for mesothelin (SMRP) by chemiluminescence enzyme immunoassay in order to examine the diagnostic and prognostic potential of TGF-β in pleural effusions and corresponding sera of individuals with malignant pleural mesothelioma (MPM). A total of 48 MPM individuals, 24 with the non-malignant pleural disease (NMPD) and 30 with stage IV lung cancer were recruited in this study. Pleural effusions from people with MPM had significantly greater TGF-β levels compared with those from NMPD or lung cancer persons. Both epithelioid and non-epithelioid MPM were related to higher TGF-β levels and levels of TGF-β associated with disease stage and with tumor volume. Moreover, high TGF-β levels in pleural effusion, yet not in serum, were significantly related to inferior OS. On the contrary, effusion SMRP levels were exclusively high in epithelioid MPM, negatively related to effusion TGF-β levels and did not give prognostic information. In summary, for diagnosis and prognostic stratification of MPM, TGF-β levels determined in pleural effusion could be a promising biomarker.