New Technique for the Diagnosis of Mesothelioma

According to Helen Davies, M.R.C.P., research fellow at the Oxford Center for Respiratory Medicine and lead author of the study,  “Pleural effusion, or the accumulation of fluid the pleural cavity, can be maddeningly difficult to diagnose as a wide variety of malignant and benign causes exist. One of the causes, malignant pleural mesothelioma, is a relatively rare cancer, but its incidence is rapidly rising on a global scale.”

Currently, the first-line test for mesothelioma in patients with pleural effusion is pleural fluid cytology, but this test is not very sensitive. Dr. Davies and her colleagues began the study to determine whether there would be additional clinical benefit to evaluating pleural fluid mesothelin, a protein released in high quantities into the pleural fluid of many patients with mesothelioma.

Researchers obtained pleural fluid samples from 209 patients referred to a specialized respiratory clinic. The levels of soluble mesothelin were measured in all samples. The results found that median pleural fluid mesothelin levels were over six times greater in patients with mesothelioma than in patients with metastatic carcinomas, and ten times greater than in patients with benign effusions.
 
Dr. Davies adds, “This study suggests a way for clinicians to more readily identify these cases from the start. Because mesothelioma has a median survival time of 12 months, minimizing the number of invasive procedures and tests patients require is crucial to reduce morbidity and the time they need to spend in the hospital. An earlier diagnosis also allows speedier interventions to relieve symptoms as well as initiation of other treatments such as chemotherapy or radiotherapy if appropriate. Claims for worker’s compensation may also be instigated once the diagnosis is confirmed.”

The majority of mesothelioma cases are caused by exposure to asbestos. Although legislation to prevent occupational exposure to asbestos has been enforced in the developed world, unrestricted contact with the substance continues in developing countries. Over 90 percent of patients diagnosed with mesothelioma present with pleural effusion and its incidence is expected to peak within the next two decades.

Dr. Davies concludes, "Pleural fluid mesothelin provides a valuable adjunct in the diagnostic assessment of patients presenting with pleural effusions, especially when cytological examination is not definitive, and can improve clinical practice."