For patients who can tolerate it, a Japanese research team says an operation to remove part of the chest lining may be the best way to diagnose early malignant pleural mesothelioma.
Pleural mesothelioma, a rare but aggressive cancer of the membrane encasing the lungs (pleura), is often difficult to diagnose. A buildup of fluid between the layers of the pleura, known as pleural effusion, is one of the first clinical signs of mesothelioma. For this reason, pleural effusion cytology is often one of the first diagnostic tests performed in suspected cases. Doctors draw off some of the pleural fluid and test it for evidence of cancer cells.
But researchers from the Department of Thoracic Surgery at Hyogo College of Medicine in Nishinomiya, Japan point out that this method has a level of sensitivity of only about 60 percent. In about half of all mesothelioma cases, they say, the initial pleural effusion cytology gives a false negative result, potentially delaying critical treatments. Instead of relying too heavily on the results of pleural effusion cytology, the Japanese doctors say more physicians should consider going a step further and performing a surgical biopsy whenever mesothelioma is suspected.
“One practical way to reduce the number of misdiagnosed malignant pleural mesothelioma is to encourage performing thoracoscopic pleural biopsy unless definitive diagnosis other than MPM is established,” they write in the International Journal of Clinical Oncology. The researchers concede, however, that even that method has its drawbacks. “There still remain a considerable number of patients with radiological/thoracoscopic malignant pleural mesothelioma who are misdiagnosed with nonspecific pleuritis after a complete investigation including thoracoscopic biopsies.”
For some of these mesothelioma patients, the research team says an even more extensive operation called a total parietal pleurectomy may be the best way of making a definitive mesothelioma diagnosis. They report performing diagnostic total parietal pleurectomy in “highly selected patients” who are suspected of have mesothelioma. These are characterized as patients with strong clinical suspicion of mesothelioma, positive pleural effusion cytology but uncertain tissue biopsy results.
During a total parietal pleurectomy, the surgeon removes the outside or parietal layer of the pleura. Because of the risk of the operation, particularly for patients in fragile overall health, some other studies have cautioned against using the approach for diagnostic purposes. The Japanese doctors require their patients to sign an informed consent form for this “highly invasive diagnostic surgery”, but contend that, by providing a confirmed diagnosis earlier, it can be lifesaving for select patients.
Hasegawa, S et al, “Practical approach to diagnoses and treat for T0 malignant pleural mesothelioma: a proposal for diagnostic total parietal pleurectomy”, January 12, 2012, International Journal of Clinical Oncology, Epub ahead of print. “Malignant Pleural Effusions: Parietal Pleurectomy”, Medscape website, Accessed January 12, 2012.