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BAP1 Can Distinguish Mesothelioma from Other Conditions

Scientist looking at mesothelioma cellsGerman scientists say a protein could help doctors distinguish mesothelioma from other conditions.

Malignant mesothelioma is a cancer that grows on the membranes around organs. These membranes are called mesothelial membranes.

But other conditions can also grow on mesothelial membranes. One of those conditions is adenomatoid tumors.

Adenomatoid tumors are benign but, even under the microscope, their cells can look a lot like malignant mesothelioma.

Now, a group of pathologists in Germany say the BAP1 protein can tell these two conditions apart. If doctors can distinguish mesothelioma from other conditions early enough, mesothelioma patients may have better outcomes.

BAP1 Loss and Mesothelioma

BAP1 is a protein encoded by the BAP1 gene. BAP1 is one of the proteins that helps keep normal cells from turning into cancer cells.

When the BAP1 gene is missing or has an error on it, a person’s body does not produce BAP1 protein. Doctors refer to this as BAP1 loss.

BAP1 loss can put a person at risk for certain kinds of cancer.  Malignant mesothelioma is one cancer that is more common in people with BAP1 loss. If people with BAP1 loss are exposed to asbestos, they are even more likely to get this rare cancer.

In the early days, it can be very hard to distinguish mesothelioma from other conditions, which can delay treatment.

Using BAP1 to Distinguish Mesothelioma from Other Conditions

In a new published article, a team of doctors in Germany say BAP1 may be the key to distinguish mesothelioma from other conditions.

They studied the BAP1 levels in 264 cases of malignant mesothelioma and 42 cases of adenomatoid tumors.

Fifty-six percent of malignant mesothelioma cases showed BAP1 loss. It was most common among people with epithelioid mesothelioma. Even the four mesothelioma samples that were most similar to adenomatoid tumors had BAP1 loss.

In contrast, none of the 42 adenomatoid tumors showed BAP1 loss. The German researchers say this shows the potential value of BAP1 to distinguish mesothelioma from other conditions.

They believe that it might even be helpful for earlier mesothelioma diagnosis.

“Surface components of malignant mesothelioma of the pleura showed concordant loss as the invasive tumor suggesting a potential role for BAP1 loss for recognizing so-called early mesothelioma,” concludes the report summary.

Mesothelioma is an extremely rare but aggressive cancer for which there is no cure. Very few of the estimated 2,500 Americans diagnosed with mesothelioma each year live longer than a year.


Erber, R, et al, “BAP1 Loss is a Useful Adjunct to Distinguish Malignant Mesothelioma Including the Adenomatoid-like Variant From Benign Adenomatoid Tumors”, January 11, 2019, Applied Immunohistochemistry and Molecular Morphology, Epub ahead of print, https://www.ncbi.nlm.nih.gov/pubmed/30640754


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