Is soluble mesothelin-related protein an upfront predictive marker of pleural mesothelioma? A prospective study on Italian workers exposed to asbestos

Objective: Soluble mesothelin-related peptide (SMRP) may be useful in the diagnosis and detection of early stage mesothelioma. We investigated the SMRP upfront predictive role for mesothelioma in asbestos-exposed workers. Methods: A total of 1,715 subjects underwent a first visit and were invited for a follow-up after 1 and 2 years, with a clinical examination and blood sampling. SMRP was measured by an ELISA assay. Results: Median SMRP at the first visit was 0.45 [interquartile range (IQR) i.e. 25th-75th percentile: 0.30-0.67 nmol/l]. In all, 1,676 subjects (97.8%) were followed up for a median period of 47.1 months. SMRP was measured at the first visit and at both follow-up visits in 1,536 subjects. At follow-up, 3 subjects were diagnosed with an epithelioid mesothelioma. In these cases, SMRP at the first visit ranged from 0.17 to 0.52 nmol/l. Malignant pleural mesothelioma was diagnosed 9-17 months after the last SMRP evaluation. No SMRP variation was observed during the follow-up. Other 61 miscellaneous cancers were diagnosed (median SMRP at first visit: 0.50 nmol/l, IQR: 0.34-0.71 nmol/l). Conclusions: Our results did not support the usefulness of SMRP as an early marker for the detection of the disease for a time interval of 1 year.