ABSTRACT

Background. Mesothelioma is a highly aggressive tumor for which there are no reliable serum tumor markers. Identification of such a marker would prove useful in the diagnosis of mesothelioma as well as for monitoring responses to therapy and screening at-risk individuals.

Methods. We assayed serum levels of soluble mesothelin-related proteins (SMR) using a double determinant ("Sandwich") ELISA in a "blinded" study of sera from 44 patients with histologically proven mesothelioma, 68 matched healthy controls, 40 of whom had been exposed to asbestos, and 161 patients with other inflammatory or malignant lung and pleural diseases.

Findings. Eighty four percent of the mesothelioma patients exhibited elevated SMR levels at a serum dilution of 1:80, compared to 1.9% of patients with other cancers or other inflammatory lung or pleural diseases and none of 28 non asbestos-exposed controls. SMR levels correlated with tumor size and increased during tumor progression. Seven of the 40 asbestos-exposed individuals exhibited increased serum SMR levels; 3 of those 7 developing mesothelioma and one developing lung carcinoma within 1 to 5 years. None of the 33 asbestos-exposed subjects whose sera had normal SMR levels and who were followed for over 8 years developed mesothelioma.

Interpretation. Determination of SMR in serum is likely to be a useful marker for the diagnosis of mesothelioma, and to monitor disease progression, and it may prove helpful for screening asbestos-exposed individuals for early evidence of mesothelioma.