Malignant pleural mesothelioma (MPM) is an aggressive, asbestos-related tumor which is increasing in incidence and causes an estimated 15,000 to 20,000 deaths per annum worldwide. Malignant pleural mesothelioma has a median survival of seven to ten months and a clinical pattern that usually involves substantial pain and dyspnea. It presents at a clinically advanced stage in most patients so there is a need for new methods of early detection. The fact that asbestos is the main etiologic agent for MPM means that at-risk populations can be readily identified and studied, and these populations represent ideal cohorts in which to undertake early cancer detection studies.

There have been a number of studies attempting to define biomarkers that could predate symptoms in a “high risk for MPM” population and also distinguish MPM from other malignancies. Unfortunately, the majority of these studies have had very few patients of various stages of MPM and the markers have not been prospectively evaluated. Some of these biomarkers include tissue polypeptide antigen, carcinoembryonic antigen, hyaluronic acid, and ferritin [1] as well as hyaluronic acid levels [2]. Other markers such as cytokeratins [3] and cancer antigen 125 (CA-125) [4] have been evaluated in MPM but have been inconclusive. One must conclude, therefore, that until recent reports of soluble mesothelin-related protein (SMRP) [5] and osteopontin [6] in MPM, there have been no reliable, validated serum or pleural effusion markers that can distinguish a highrisk, asbestos-exposed population without MPM from patients with established MPM, or to distinguish other malignancies from MPM.