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 asbestos-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.