Researchers from Hiroshima University say they have found a nearly foolproof way to tell the difference between epithelioid mesothelioma and lung cancer.
This is critical because the prognosis can be very different between the two. They are also treated differently.
But epithelioid mesothelioma and lung cancer are similar in many ways. They cause many of the same symptoms. Even their cells look similar under the microscope. This can make it hard for doctors to deliver an accurate and timely diagnosis.
If the new findings are right, the biomarker identified by the Hiroshima researchers could be a diagnostic gamechanger.
Lung Adenocarcinoma or Pleural Mesothelioma?
At first glance, epithelioid mesothelioma and lung cancer seem to be very different. Mesothelioma makes up about 0.3 percent of all cancers in the US. Lung cancer makes up about 25 percent.
Malignant mesothelioma is a membrane cancer. It can occur on the membrane surrounding the abdominal organs, the membrane around the heart, or the pleural membrane around the lungs. The pleural location is the most common.
Lung adenocarcinoma (a type of non-small cell lung cancer) starts in the lung tissue. It eventually causes shortness of breath, coughing, and chest pain.
As pleural mesothelioma tumors grow, it gets harder for the lungs to expand. These patients also develop shortness of breath, coughing, and chest pain.
Epithelioid mesothelioma and lung cancer both grow quickly but they respond to different treatments. Being able to tell them apart is critical to choosing the right therapy.
SOX6 in Epithelioid Mesothelioma and Lung Cancer
Immunohistochemistry is a way of learning about cancer cells. It uses chemical stains to measure the amount of certain proteins in the cells. Different kinds of cells have different protein profiles.
The Hiroshima research team focused on the DNA-binding protein SOX6. They looked at gene expression data from 54 epithelioid mesothelioma patients and 69 lung cancer patients.
They found SOX6 in nearly every mesothelioma patient but in only a handful of lung cancer patients.
“SOX6 expression was present in 53 of 54 (98%) cases of epithelioid mesothelioma, compared with its expression in only 5 of 69 (7%) cases of lung adenocarcinoma,” writes lead author Takahiro Kambara.
SOX6 correctly distinguished between epithelioid mesothelioma and lung cancer 98 percent of the time. In fact, SOX6 was much better at telling the difference than other common biomarkers. It also worked well in combination with other markers.
“In conclusion, SOX6 is a novel candidate immunohistochemical marker for differentiating epithelioid mesothelioma from lung adenocarcinoma,” writes Dr. Kambara.
About 3,000 people in the US receive a mesothelioma diagnosis each year. Most of them have lived or worked around asbestos.
Kambara, T, et al, “SOX6 Is a Novel Immunohistochemical Marker for Differential Diagnosis of Epithelioid Mesothelioma From Lung Adenocarcinoma”, June 2, 2020, American Journal of Surgical Pathology, https://journals.lww.com/ajsp/Abstract/9000/SOX6_is_a_Novel_Immunohistochemical_Marker_for.97424.aspx