Biomarkers in Pleural Effusions Can Improve Mesothelioma Diagnosis

Italian scientists say some newly identified biomarkers in pleural effusions are very good at ruling out mesothelioma in patients who do not have the disease. 

Unfortunately, most of these biomarkers are not as good as positively identifying mesothelioma. But their accuracy can be improved by combining several of them. 

Pleural effusions are pockets of excess fluid that collect around the lungs of people with certain kinds of cancer and other conditions. 

Mesothelioma biomarkers in pleural effusions are proteins and other substances that are mostly found in mesothelioma patients. The new study suggests that using these biomarkers the right way can lead to more accurate diagnoses.

The Importance of Biomarkers in Pleural Effusions

Pleural mesothelioma is a rare cancer of the lung lining. It is a challenge to diagnose. The early symptoms can be as vague as cough and fatigue. But accurate diagnosis is often the difference between life and death. 

As tumors grow, many mesothelioma patients produce pleural effusions or ‘water on the lungs’. This is a byproduct of the body’s attempt to fight disease. This fluid buildup is very common with pleural mesothelioma. But not all people with pleural effusions have mesothelioma. 

It is easier and safer to draw off some of this fluid than to perform a tissue biopsy. The fluid may contain proteins, metabolites, genetic material, and even cancer cells. These biomarkers in pleural effusions can help doctors identify the patient’s underlying health condition. 

If pathologists know what they are looking for, tests of the fluid may point strongly toward or away from malignant mesothelioma. 

How Accurate Are These Tests?

Tissue biopsy is still the only way to know for sure if a patient has mesothelioma. Even then, it is not easy to diagnose. 

But the new Italian study suggests that biomarkers in pleural effusions are the next best thing. Researchers searched the medical literature for studies on some of the newest mesothelioma biomarkers in pleural effusions. They looked for articles on:

• BRCA1-associated protein a (BAP1) loss
• methylthioadenosine (MTAP)
• 5-hydroxymethylcitosine (5-hmC)
• glucose transporter 1 (GLUT1)
• insulin like-growth factor II messenger RNA-binding protein 3 (IMP3)
• enhanced zeste homologue 2 (EZH2) staining
• cyclin-dependent kinase inhibitor 2A (CDKN2A) homozygous deletion (HD) testing
• soluble mesothelin
• microRNA quantification

The team assessed the quality of the evidence in each study. Several of the biomarkers in pleural effusions were close to 100 percent accurate at ruling out mesothelioma.

Most were not as good at correctly identifying it. But the researchers say there is a way to improve the odds of an accurate mesothelioma diagnosis.

“Their moderate sensitivity on their own, however, can be significantly improved by the use of 2 biomarkers, such as a combination of BAP1 and CDKN2A with fluorescence in situ hybridization or a combination of BAP1 and MTAP immunohistochemistry,” they write in Cancer Cytopathology. 

Pleural mesothelioma accounts for 4 out of 5 mesothelioma cases. In the US, that amounts to about 2,000 people every year.

Source: 

Girolami, I, et al, “Evidence-based diagnostic performance of novel biomarkers for the diagnosis of malignant mesothelioma in effusion cytology”, September 3, 2021, Cancer Cytopathology, https://acsjournals.onlinelibrary.wiley.com/doi/10.1002/cncy.22509