Aug 20, 2012 - Potential New Diagnostic and Prognostic Marker for Pleural Mesothelioma
Japanese scientists have discovered what they consider to be a potential new diagnostic and prognostic marker for pleural mesothelioma patients. New research from the Department of Thoracic Surgery at the Hyogo College of Medicine in Nishinomiya, Japan shows that by examining circulating endothelial cells (CEC) in malignant pleural mesothelioma patients, doctors can very accurately identify this deadly asbestos disease. However, the study, results of which were published in the annals of Surgical Oncology, also demonstrates that levels of CECs can be used as a prognostic tool as well.
Circulating endothelial cells break away from the lining of blood vessels and lymphatic vessels and are free-floating in a person’s blood stream. The Japanese researchers theorized that if these blood cells could be captured and analyzed that perhaps they could be used to identify mesothelioma in previously undiagnosed patients.
To that end, they withdrew blood samples from patients suspected of having but not yet diagnosed with mesothelioma. They then analyzed 4.0 mL samples using an automated system which effectively captured the circulating endothelial cells but only those expressing an anti-CD146 antibody. CD146 is also known as cell surface glycoprotein MUC18 and is a surface protein only expressed by certain cells. The presence of an antibody specifically targeting CD146 indicates the presence of the cluster itself.
The scientists used this particular method because CD146 had previously been identified in patients with melanoma.
The researchers pulled these samples from 109 eligible patients. Thirty of those were eventually diagnosed with non-malignant diseases but 79 were later confirmed as suffering from malignant pleural mesothelioma (MPM).
Among the observations the research team made was the significantly higher amounts of CECs in the blood of patients eventually diagnosed with MPM. In fact, mesothelioma patients demonstrated rates of CECs that were over three-times that of those not suffering from the disease.
Drawing from this, the team applied a receiver operating characteristic (ROC) curve analysis, a mathematical equation which isolates true positives from false positives, and discovered that indeed the presence and concentration of CECs in blood samples did provided “a significant diagnostic performance in discrimination between MPM and nonmalignant diseases.”
Why were the CECs higher in patients diagnosed with malignant pleural mesothelioma? The concentration of CECs was shown to directly correlate to intratumoral microvessel density (MVD). MVD is actually a measure of tumor angiogenesis, the growth of blood vessels that feed cancerous cells within tumors.
Additionally, higher numbers of these circulating endothelial cells directly correlated to the individual patient’s prognosis. Scientists discovered that a CEC count greater than 50 equated to a median mesothelioma survival rate of just over 11 months as opposed to 20 months in patients with CEC counts lower than that.
While any real-world applications of this discovery is a long time coming, the results of the Japanese study could very well lead to a quicker, less-expensive test for pleural mesothelioma or at least aid in the patient screening process.
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