Researchers from Japan found a new immunohistochemical marker, glypican-1, that can be used to differentiate cases of epithelioid mesothelioma from lung adenocarcinoma. They explained histological morphology, or cell type, is not enough on its own to properly make a mesothelioma diagnosis or be able to develop the most effective treatment plan.
Mesothelioma is often misdiagnosed as other cancers and diseases, with lung adenocarcinoma among the most common since it also expresses other common markers of mesothelioma. Adenocarcinoma, the most common type of lung cancer, is also commonly made up of glandular epithelial cells. Since 50% – 70% of mesothelioma cases are made up of the epithelial cell type and most commonly pleural mesothelioma, found in the lining of the lung, properly differentiating these two cancers can be quite difficult. Experts largely agree that the best way to accurately differentiate two similar diagnoses is through researching specific cellular stains under a microscope.
Glypican-1 is a protein that has already been identified as a marker for other cancers, like pancreatic cancer. Other studies have also alluded to the idea that the protein plays a large role in cell division and growth regulation. To determine if the protein may also be a marker of epithelioid mesothelioma, the researchers studied 82 mesothelioma patients and 97 cases of lung adenocarcinoma for expression of the protein.
The researchers took biopsies from the patients and used an immunohistochemistry process to identify the protein. Immunohistochemistry consists of making a stain that can selectively image specific proteins, like glypican-1, by using different antibodies that will bind to the agent and be able to be viewed under a microscope.
They determined all 82 patients diagnosed with epithelioid mesothelioma expressed the protein strongly, while it was only detected in three cases of lung adenocarcinoma and was not a dominant expression. Determining the appropriate cell type, as well as properly differentiating mesothelioma from other diseases, is commonly stated to be one of the most important prognostic factors for patients.
Overall, the researchers found expression of glypican-1 had 100% sensitivity, 97% specificity, and a 98% accuracy rate to differentiate epithelioid mesothelioma from lung adenocarcinoma. They noted these findings matched the sensitivity of other common mesothelioma markers calretinin and D2-40, but provided an even more specific diagnosis than these two markers.
Since early detection of mesothelioma is so important to the development of an appropriate treatment plan for the aggressive cancer, discovery of this protein for patients with this cell type can have a great impact on their life expectancy.