Soluble Mesothelin-related Protein Levels in Subjects With Malignant Mesothelioma

Abstract

PP-30-155 Background/Aims: Malignant mesothelioma is a highly aggressive tumor associated mostly with asbestos exposure. Soluble mesothelin-related protein (SMRP) is a potential tumor marker for mesothelioma. The aim of this study was to determine the differences in serum SMRP levels at various phases of the disease before and during treatment. Methods: The study included all 78 subjects with mesothelioma treated at the Institute of Oncology, Ljubljana, between 2007 and 2009. According to the cumulative asbestos exposure, they were divided into 4 groups (nonexposed, low, medium, and high). Serum samples were collected in all subjects before the treatment and/or in different responses to treatment (complete response, partial response, stagnation, progressive disease). Serum SMRP levels were determined by enzyme-linked immunosorbent assay with 2 monoclonal antibodies. Results: Asbestos exposure was confirmed in 67 (85.9%) subjects. Only occupational exposure was observed in 32 subjects, only environmental in 12 subjects, and both occupational and environmental exposures in 23 subjects. The cumulative asbestos exposure was classified as low in 24, medium in 21, and high in 22 subjects. Mean serum SMRP was 5.75 nM before the treatment, 0.00 nM in complete response, 1.33 nM in partial response, 2.97 nM in stagnation, and 9.67 nM in progressive disease. The SMRP levels were significantly higher before the treatment compared to the stagnation, partial and complete responses to treatment (t = 2.49; P = 0.016), as well as in the progressive disease if compared to the stagnation, partial and complete responses to treatment (t 5.48; P 0.000). Conclusion: Asbestos exposure was confirmed in almost 86% of subjects with mesothelioma and among them, the exposure was low in 36% of subjects. As the findings of the study suggest that SMRP might be a useful tumor marker for detecting the progression of mesothelioma and tumor response to treatment, a thorough follow-up of a prospective cohort is needed.