Proteins expressed by mesothelioma cells may be the basis for a blood marker that is effective in disease screening and in subsequent monitoring of response to treatment, according to an article in the November 15th issue of The Lancet.

Dr. Bruce W. S. Robinson and his Australian colleagues developed a test to assess blood concentrations of proteins expressed by mesothelioma cells that are called soluble mesothelin-related proteins. The test had a high level of specificity: 37 (84 percent) of 44 patients with mesothelioma had raised concentrations of soluble mesothelin-related proteins compared with 3 (2 percent) of 160 patients with other cancers or other inflammatory lung or pleural diseases and with none (0 of 28) of the controls who had not been exposed to asbestos.

The investigators suggest that soluble mesothelin-related proteins could be a useful way to monitor the tumor's growth as concentrations in the study population correlated with tumor size, increasing during periods of tumor progression.

Robinson commented, "On the basis of our data we propose that measurement of soluble mesothelin-related protein concentrations in serum is a useful adjunct in the diagnosis of mesothelioma. Blood concentrations should be monitored in asbestos-exposed individuals who are at risk of developing mesothelioma to determine if early therapeutic intervention improves patients' outcome."

He added, "Importantly for the hundreds of thousands of asbestos-exposed people who are at risk of this cancer, the test can detect the cancer several years before it presents. Of 7 asbestos-exposed individuals who had increased blood concentrations of soluble mesothelin-related proteins, 3 developed mesothelioma and 1 developed lung cancer within 1-5 years whereas none of the 33 asbestos-exposed participants whose blood samples had normal concentrations of soluble mesothelin-related proteins developed mesothelioma in that time."