One of the biggest challenges for patients and clinicians dealing with malignant pleural mesothelioma is just getting a definitive diagnosis. Although mesothelioma is closely associated with asbestos, symptoms may not show up until decades after exposure, making it difficult to link the cause and effect. When symptoms such as chest pain and shortness of breath do occur, they are often attributed to other, less serious causes.
But a recent article in Lung Cancer focuses on a promising new way to help distinguish mesothelioma from other conditions with similar characteristics. Researchers at the University of Chicago and cancer centers in the UK, France, and Japan say a glucose transport protein called GLUT-1 was present in half of the epithelioid mesothelioma cells tested and three quarters of the sarcomatoid mesothelioma cells.
For this retrospective study, the authors performed immunohistochemical staining for the presence of GLUT-1 in tissue samples from 70 people with mesothelioma, 31 people with a benign condition called mesothelial hyperplasia, and 29 people with benign fibrosing pleuritis. Forty-one of the mesothelioma samples were from patients with the epithelioid variety and 29 from those who had sarcomatoid mesothelioma. Slides from all cell samples were scored by pathologists based on the percentage of cells in the samples that were positive for GLUT-1.
The study found that all benign samples were negative for GLUT-1. However, 58% of the malignant mesothelioma samples stained positive for GLUT-1, to varying degrees. Twenty-one of the 41 epithelioid mesothelioma cell samples were positive for GLUT-1 and 21 of the 29 sarcomatoid mesothelioma samples were positive. In addition, there were 3 biphasic mesothelioma samples (the least common type of mesothelioma), all of which tested positive for GLUT-1.
The authors caution that GLUT-1 testing does have its limitations and that a negative stain does not necessarily exclude the diagnosis of mesothelioma, but say it could be an important new diagnostic tool. “As with all immunohistochemical stains used for diagnostic purposes, GLUT-1 has to be a part of a panel and the results interpreted in the context of clinical, radiological, and histological findings,” they concluded.
Husain, AN, et al, “How useful is GLUT-1 in differentiating mesothelial hyperplasia and fibrosing pleuritis from epithelioid and sarcomatoid mesotheliomas? An international collaborative study”, December 30, 2013, Lung Cancer, Epub head of print.