Hyaluronan in serum as an indicator of progressive disease in hyaluronan-producing malignant mesothelioma.

Malignant pleural mesothelioma is associated in up to 70% of cases with an elevated content of hyaluronan (HYA) in the pleural fluid. Increased levels of circulating HYA have also been described. The clinical course of the disease can be followed by computed tomography (CT), although there are disadvantages with serial CT scans. An easily analyzed blood test, such as HYA in serum, would be of value for clinical follow-up. The purpose of this study was to relate changes in serum HYA to changes in quantitative estimations of tumor volume in cases of mesothelioma. The content of HYA in the pleural fluid was analyzed in 19 men with mesothelioma. CT scans were performed about every third month. The tumor volume was estimated on transilluminated CT scans with a digital planimeter. Blood samples for HYA analyses were drawn every month. The impact of the tumor burden on HYA in serum was indicated in statistical analysis by a straight line for each patient according to the restricted maximum likelihood method. An elevated content of HYA, i.e., >100 mg/L, in the pleural fluid was seen in 13 of 19 patients. There was a positive correlation, although low, between the initial level of HYA in serum and the concentration of HYA in pleural fluid. Increasing levels of circulating HYA were on average accompanied by an increase in tumor volume in the HYA-producing group of mesotheliomas (P = 0.01). This was not seen in the non-HYA-producing mesotheliomas (P = 0.10). These results provide evidence that it should be possible to follow the clinical course of malignant pleural mesothelioma patients by analysis of circulating HYA in the subgroup of HYA-synthesizing mesotheliomas.