Danish Researchers Link New Biomarker to Mesothelioma Diagnosis
March 13, 2012
A trio of Danish researchers from University Hospital of Copenhagen have published an encouraging study that should help lead to a faster diagnosis of malignant pleural mesothelioma.
One of the things that had made MPM so difficult to treat in the past is that the diagnosis typically comes so late, well after the cancer has spread, often eliminating surgery as an option.
Mesothelioma is the cancer caused exclusively by an exposure to asbestos. It also has a lengthy latency period (10-50 years) between exposure and diagnosis.
Early symptoms often mimic less serious lung conditions. And because mesothelioma is rare, with an estimated 3,000 patients diagnosed in the United States annually, most physicians are not familiar with it.
Too often the diagnosis comes too late.
A typical diagnosis comes with a grim prognosis that includes six to 18 months to live. Longer survivors usually are the ones who were fortunate enough to be diagnosed early. Symptoms often include a persistent dry cough, fatigue, shortness of breath and reduced respiratory function.
Anyone who has spent years in an occupation where asbestos exposure is common would be advised to consult a doctor with experience in treating mesothelioma.
A confirmed diagnosis usually doesn’t come until 3-6 months after a patient’s first symptoms and consultation with a physician.
The Danish study uncovered a new biomarker — the absence of methylthioadenosine phosphorylase (MTAP) — in mesothelioma cells. Doctors often have relied on other biomarkers in the blood or lung fluid, and then scans or X-rays, before recommending a more complex thoracoscopic biopsy, which is the most accurate and reliable confirmation.
The goal of the Danish study was determining whether the decrease or absence of MTAP, through immunohistochemistry testing, could be detected and used as a diagnostic marker.
The test included measuring the MTAP levels in lung fluid of 99 MPM patients, along with 39 patients who had mesothelial proliferation.
Researchers discovered that 65 percent of the mesothelioma patients had decreased MTAP, while only 23 percent of the other patients did. In a second test with other patients, they found a decreased MTAP expression with a sensitivity of 71 percent and a specificity of 90 percent.
The determination of the researchers was that the decreased MTAP could be useful in combination with other markers in regard to MPM. The study was done by the Department of Pathology.
Other early diagnostic tools include the Mesomark assay, which measures the amount of soluble mesothelin-related protein in human serum; and the miRview meso test, which measures tissue-specific micro RNA biomarkers.