Clapper, Patti, Schweizer and Mason

Mesothelioma is an aggressive cancer caused by prior exposure to asbestos that begins in the lining of the lungs (pleural mesothelioma, the most common form), the abdomen (peritoneal mesothelioma), or the heart (pericardial mesothelioma.)  Because all forms of mesothelioma have a long latency period of ten to forty years between time of initial exposure and development of symptoms, the cancer is not diagnosed until it has reached advanced, incurable stages.  Conventional treatments then have very little effect on slowing down the progression and are merely palliative in focus.

Therefore, the ability to find ways to diagnose mesothelioma at earlier stages is imperative to improve treatment efficacy as well as prolong survival.  Clinical trials through the National Cancer Institute and other research facilities continue to search for ways to diagnose this disease earlier as well as find ways to prevent it in populations with known prior exposure histories.

Researchers from Hyogo College of Medicine and Hyogo Prefectural Tsukaguchi Hospital in Japan have discovered that pleural effusion VEGF levels can be used as a prognostic factor for diagnosing malignant pleural mesothelioma (MPM) at earlier stages.  VEGF, vascular endothelial growth factor, is a substance made by cells that stimulate new blood vessel formations, causing increased cell division in the endothelial lining.  In simple terms, it creates an increased growth rate of malignant cells. 

VEGF’s normal and healthy function is to create new blood cells when there has been injury or blood vessels become blocked for some reason.  However, when VEGF is overexpressed, it can contribute to acceleration of cancer, including mesothelioma, by supplying oxygen through blood to tumors that normally would not survive or metastasize.

Results from the current study in Japan confirm that patients diagnosed with MPM have significantly higher pleural effusion VEGF levels, especially those with advanced stage mesothelioma.  Researchers therefore suggest that VEGF levels could be used as a tool in predicting the presence of and being a prognostic marker for MPM.  If mesothelioma could be diagnosed at earlier stages then early therapeutic interventions could be much more beneficial versus late intervention.

The study also confirms that VEGF expressed in MPM acts as an autocrine growth factor, meaning that it acts to produce even more cancer cells and increases the growth factor of mesothelioma.  Antagonists of autocrine growth factors can slow down cancer progression and, in some animal studies, have been proven to control aberrant cancer cell growth.   So expression of VEGF could be used not only as a biomarker to diagnose mesothelioma, but also then known antagonists could be administered to the patient earlier to counteract cancer cell growth, significantly slowing down progression and proliferation.

Results from this study of 16 patients diagnosed with mesothelioma also showed that VEGF levels increased with disease progression, and that this correlation suggests that VEGF could be used to estimate prognosis as well.  The higher the VEGF levels, the more advanced the disease, leading to shorter survival times.

If used as a biomarker, this research could be very useful to prolonging survival times for those with known prior exposure to asbestos or those who begin experiencing symptoms of mesothelioma and seek help immediately.  The only known patients to survive as long as five years have been diagnosed at early stages of the disease.  If VEGF levels could be used to detect mesothelioma earlier, patients could get therapeutic interventions that would significantly increase their survival as well as quality of life.