New Biomarker May Detect Mesothelioma Earlier

Researchers at one of the country’s top cancer centers say they have found an effective way to diagnose mesothelioma earlier. Their findings are published in the latest issue of the prestigious New England Journal of Medicine.

Fibulin-3 is a protein that is expressed in the membranes of blood vessels. A single mutation in the gene that encodes fibulin-3 has been implicated in a form of macular degeneration. Now, study author and professor of thoracic oncology Harvey Pass, MD, and his colleagues at New York University’s Langone Medical Center believe that fibulin-3 levels in the blood and pleural effusions (fluid around the lungs) can distinguish mesothelioma patients from those who have been exposed to asbestos but do not have the disease. It can also distinguish between mesothelioma and other causes of fluid buildup.

To test the protein’s diagnostic value, researchers measured fibulin-3 levels in the blood plasma of 92 patients with mesothelioma, 136 asbestos-exposed patients, 93 patients with fluid buildup but no mesothelioma, and 43 healthy people with no asbestos exposure. They found that plasma levels of fibulin-3 did not vary with age, sex or duration of asbestos exposure and were “significantly higher” in patients with pleural mesothelioma.

The results were similar when the researchers measured levels of fibulin-3 in pleural effusions. Fluid was taken from 74 mesothelioma patients, 39 patients with effusions but no cancer, and 54 with malignant effusions that were not caused by mesothelioma. Among these patients, effusion fibulin-3 levels were also significantly higher in patients whose pleural effusions were a direct result of mesothelioma.

“In a comparison of patients with early-stage mesothelioma with asbestos-exposed persons, the sensitivity was 100% and the specificity was 94.1%,” reports the team in a published summary of their results. This could make fibulin-3 an important new tool in the effort to diagnose mesothelioma earlier, when treatment is more likely to be effective.

Mesothelioma develops in the membranes that line the chest, abdomen and heart. Exposure to asbestos is the primary cause. Because the disease tends to have few symptoms until in its later stages, by the time many patients are diagnosed, the prognosis is often poor. In 2005, Dr. Pass and his team demonstrated the potential diagnostic value of another biomarker called osteopontin, but Pass tells Medline Plus that fibluin-3 is a far more effective mesothelioma marker.

The potential of fibulin-3 as a mesothelioma diagnostic marker will need to be confirmed in further tests.  If proven to be reliable over a larger number of patients, this test will help clinicians detect mesothelioma in asbestos-exposed individuals even before symptoms occur.

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