Comparison of osteopontin, megakaryocyte potentiating factor, and mesothelin proteins as markers in the serum of patients with malignant mesothelioma.

INTRODUCTION: There is increasing interest in identifying a blood-based marker for the asbestos-related tumor, malignant mesothelioma. Three potential markers for mesothelioma are mesothelin, megakaryocyte potentiating factor (MPF) and osteopontin. The purpose of the current study was to directly compare these biomarkers in the same sample population, determining their sensitivity and specificity in establishing a diagnosis, and to determine if diagnostic accuracy for mesothelioma is improved by combining the data from all three markers.
METHODS: Serum levels of mesothelin, MPF and osteopontin were determined by commercially available assays in 66 samples from patients with pleural malignant mesothelioma, 20 healthy individuals, 21 patients with asbestos-related lung or pleural disease, 30 patients presenting with benign pleural effusions and 30 patients with other malignancies.
RESULTS: Serum levels of the three markers were elevated in mesothelioma patients. At a level of specificity of 95% relative to healthy controls and patients with benign asbestos related disease, the sensitivity for mesothelioma was 34% for MPF, 47% for osteopontin and 73% for mesothelin. Osteopontin and MPF were unable to differentiate patients with mesothelioma from patients with other malignancies or those presenting with transudative pleural effusions. Combining the data from the three biomarkers using a logistic regression model did not improve sensitivity for detecting mesothelioma above that of the mesothelin marker alone.
CONCLUSION: Serum mesothelin remains the most specific marker for the diagnosis of mesothelioma.