Testing for certain biomarkers in lung fluid may offer a reliable way to help diagnose malignant mesothelioma, even without a tissue biopsy.
Diagnosing mesothelioma from lung fluid alone is controversial. But pathology researchers in Seattle and Vancouver compared mesothelioma biomarkers BAP1 and p16 in lung fluid and tissue samples in 15 mesothelioma patients and got nearly identical results.
Lung Fluid vs. Biopsy – Which was better?
The tests included 15 patients with epithelial mesothelioma and 3 with benign mesothelial disease. Matched samples of tumor cells and lung fluid cells were tested for mutations in the BAP1 gene and for deletion of the p16 gene. Four of the fluid samples could only be tested for BAP1 but didn’t contain enough cells for p16 testing. Of the 11 remaining matched fluid/tissue samples, every single one showed either BAP1 mutation or p16 deletion or both.
BAP1 loss alone was found in 10 out of 15 of the tissue biopsies and 10 out of 15 fluid samples. P16 deletion was found in 12 out of 15 of the biopsies and 8 of the 11 evaluable fluid samples.
Forty-seven percent of the mesothelioma tissue samples and 42 percent of the fluid samples showed changes in both biomarkers. Just as importantly, none of the tissue or fluid samples from people with the benign mesothelial disease showed changes in either of the biomarkers.
Lead researcher Dr. Harry Hwang of PhenoPath Laboratories in Seattlee concluded that
“Both BAP1 immunohistochemistry and p16 FISH analysis provide reliable markers of mesothelial malignancy [mesothelioma] in effusion cytology specimens.”
That is especially true if the fluid sample has plenty of the atypical cells that indicate mesothelioma.
Easier Mesothelioma Testing
Most people with mesothelioma (and many with other types of cancer) develop excess fluid in the pleural cavity around the lungs.
This fluid can be drawn off with a needle in an outpatient procedure for testing.
Hwang, HC, et al, “Utility of BAP1 Immunohistochemistry and p16 FISH in the Diagnosis of Malignant Mesothelioma in Effusion Cytology Specimens”, October 6, 2015, American Journal of Surgical Pathology, Epub ahead of print