Mesothelioma is not only a difficult cancer to treat. It’s also notoriously difficult to diagnose. Because there are no definitive biomarkers that can quickly reveal if a patient has this aggressive cancer, diagnosing mesothelioma typically involves a combination of different techniques.
A new article in the Archives of Pathology and Laboratory Medicine highlights some of the most useful and important diagnostic tests for mesothelioma. Pathologists Qudsia Arif, MD, and Aliya Husain, MD, of the University of Chicago used peer-reviewed publications, text books, and consensus among their fellow pathologists to compile their recommendations.
According to the report, among the possible diagnostic biomarkers for mesothelioma, four of the most reliable are the proteins calretinin, WT-1, cytokeratin 5/6, and podoplanin. These, say the authors, should be used in conjunction with imaging studies, a thorough exam, and patient history of asbestos exposure.
“It is recommended that at least 2 mesothelial and 2 carcinoma markers with greater than 80% sensitivity and specificity be used for the diagnosis of mesothelioma when all clinical, radiologic, and histologic features are concordant,” write Arif and Husain.
In addition, the authors note that a tumor suppressor molecule called p16, which is sometimes used to diagnose other types of cancer, is missing in up to 70 percent of cases of epithelioid mesothelioma and in almost all cases of sarcomatoid pleural mesothelioma. This molecule may be especially helpful in mesothelioma diagnosis since p16 deletion has never been found in any non-malignant mesothelial tumor.
Finally, the way suspected mesothelioma cells appear when examined under the microscope is key to not only making a definitive diagnosis but also to predicting treatment response and prognosis. Mesothelioma tumors in which more than ten percent of the cells are “pleomorphic” or varied in shape and size are typically more aggressive and linked to poor survival. Although it has not been confirmed by any large studies, there is also evidence that nuclear grade, a method of classifying the nuclei of mesothelioma cells under the microscope, may also be used for prognosis.
Arif, Q and Husain, AN, “Malignant Mesothelioma Diagnosis”, Archives of Pathology and Laboratory Medicine, August 2015, pp. 978-980.