Soluble mesothelin-related protein for malignant pleural mesothelioma screening Introduction: Malignant Pleural Mesothelioma (MPM) is a tumor of the mesothelial cells related to asbestos exposure. This malignancy is extremely aggressive, with poor response to different treatment modalities, and it has a mean survival of 8 months since diagnosis. With the introduction of new chemotherapeutic agents and trimodality protocols, five-year survival of 40% in initial stages has been reported. Serum detection of Soluble Mesothelin-related Protein (SMRP) could be used for screening of MPM. Using the MESOMARK® test, 53% of MPM patients had levels greater than 1,5 nM, while 99% of control patients had lower concentrations. The aim of this study is to evaluate the use of this test in Chile and determine its utility for screening of MPM. Methods: Quantitative blind measurement of serum SMRP by MESOMARK® test. We studied 3 groups: 8 workers exposed to asbestos, 5 patients with diagnosed MPM and 14 age matched workers without known exposure to asbestos. Participants were informed of the study. Results: Mean ± standard deviation SMRP levels in the control group was 0,53 ± 0,4 nM, 0,89 ± 0,46 nM in patients exposed to asbestos and 10,68 ± 10,28 nM in MPM patients. Differences between the groups were statistically significant (p = 0,02). In the MPM group, 3 patients were found to have SMRP levels greater than 1,5 nM (17,27 nM; SD 6,95) and 2 patients normal values (0,79 nM; SD 0,32). Using a cutoff value of 1,5 nM, sensitivity of the test was 60% and specificity was 100%. Conclusions: Detection of SMRP levels allowed to identify patients with MPM, three of whom had very high concentrations. The sensitivity and specificity found is similar to that previously reported. If our results are confirmed in greater studies, SMRP detection could be used for screening of MPM.