Biomarkers distinguish between mesothelioma and non-cancer

A team at the Copenhagen University Hospital in Denmark have identified four biomarkers which could help identify between malignant pleural mesothelioma (MPM) and non-cancerous pleural tissue with reactive mesothelial proliferations (RMPs). 

This is a common but difficult diagnostic problem in pleural biopsy samples taken from patients who have suspected MPM. The ability to make quicker and more accurate diagnoses could help improve patient outcomes. 

The study, which was published in the Journal of Molecular Diagnostics, aimed to find microRNAs, which are small, non-coding RNA strands made of around 22 nucleotides. They were of interest as previous research has shown their ability to be diagnostic, prognostic and predictive markers in other cancers.

"Our goal was to identify microRNAs (miRNAs) that can aid in the differential diagnosis of MPM from RMPs," says lead investigator Dr Eric Santoni-Rugiu of the laboratory of molecular pathology at the Department of Pathology of Rigshospitalet at Copenhagen University Hospital.

After screening 742 miRNAs, the team identified miR-126, miR-143, miR-145, and miR-652 as the strongest candidates to aid the diagnosis of MPM. Using results from these four miRNAs, tissue samples from patients with known outcomes could be classified as MPM or non-cancerous with an accuracy of 0.94, sensitivity of 0.95, and specificity of 0.93. 

Furthermore, Dr Santoni-Rugiu and his team made an association between miRNA levels and patient survival.

"The International Mesothelioma Interest Group (IMIG) recommends that a diagnostic marker of MPM have sensitivity/specificity of >0.80, and these criteria are fulfilled by our miRNA classifier," he added. 

According to the authors, the accuracy of diagnosis could be further improved by adding immunohistochemical testing of miRNA targets in biopsy tissue to their miRNA assay, as this could enable analysis of samples with low-tumour cell count.

Distinguishing MPM from noncancerous abnormalities can be difficult as there are no generally-accepted diagnostic biomarkers to distinguish between the two conditions. This often leads to later diagnosis when the patient is at a more advanced stage, meaning that less than 20 per cent of patients can be treated surgically.