Background Diagnosis of malignant mesothelioma is frequently difficult, the most common differential diagnosis being reactive pleural conditions and metastatic adenocarcinoma. Soluble mesothelin levels in serum have recently been shown to be highly specific and moderately sensitive for mesothelioma. So as most mesothelioma patients present with exudative effusions of either the pleura or peritoneum, we sought to determine if levels of mesothelin were elevated in these fluids and if any elevations could help distinguish mesothelioma from other causes of exudative effusion.
Patients and Methods Pleural fluid was collected from 192 patients who presented to respiratory clinics; 52 patients with malignant mesothelioma, 56 with non- mesotheliomatous malignancies and 84 with effusions of non-neoplastic origin. Peritoneal fluid was collected from 42 patients; 7 with mesothelioma, 14 with non- mesotheliomatous malignancies and 21 benign effusions. Mesothelin levels were determined on effusion and serum samples by ELISA.
Results Mesothelin was statistically significantly higher in effusions of patients with mesothelioma; with a specificity of 98% the assay had a sensitivity of 67% comparing mesothelioma patients to patients with effusions of non-neoplastic origin. In 7 out of 10 cases mesothelin was elevated in the effusion collected 3 weeks to 10 months before the diagnosis of mesothelioma was made, and in 4 out of 8 of these cases mesothelin was elevated in the effusion but not in the serum.
Conclusions Measurement of mesothelin concentrations in the pleural and/or peritoneal effusion of patients may aid in the differential diagnosis of mesothelioma in patients presenting with effusions.
- tumour marker