Osteopontin Levels in an Asbestos-Exposed Population

Purpose: Serum osteopontin levels in patients with malignant mesothelioma have been reported to be higher than in healthy subjects. This study assessed serum osteopontin levels in an asbestos-exposed population to test whether nonmalignant asbestos-related disorders could influence osteopontin levels. Experimental Design: This cross-sectional study evaluated serum osteopontin levels in 525 male subjects. Subjects were classified into six different diagnostic groups, including asbestosis (n = 23), silicosis (n = 20), diffuse pleural thickening (n = 110), asbestosis and diffuse pleural thickening (n = 13), pleural plaques (n = 142), and healthy subjects with a history of asbestos exposure (n = 217). Results: Mean serum osteopontin levels differed among the six groups (P < 0.0001). Mean osteopontin values of the healthy individuals exposed to asbestos were significantly different from that of subjects with asbestosis (P < 0.001) and diffuse pleural thickening (P < 0.001). There was a significant difference in mean serum levels of osteopontin in healthy individuals exposed to asbestos (n = 217) compared with the group mean of all subjects with a sbestos-related disorders (n = 288; P < 0.0001). Conclusions: Our results suggest that osteopontin levels are elevated in subjects with asbestos-related disorders without malignant mesothelioma. These data indicate that osteopontin, although reported to be useful for detecting malignant mesothelioma in asbestos-exposed individuals, may be influenced by nonmalignant processes.