Clapper, Patti, Schweizer and Mason

Australian researchers looking for a way to detect mesothelioma earlier in the disease’s progression have locked on to microRNAs as possible indicators.  It is their hope that a test can be devised using these tiny molecules to positively identify the presence of mesothelioma cancers in patients without having to wait until symptoms are noticed. 

Since mesothelioma has such a long latency period (sometimes as long as 50 years or more) patients don’t often notice symptoms until the disease has progressed into stage 4 terminal cancer.  Not only that, even when symptoms do arise, they’re often misdiagnosed because they closely mimic symptoms of other medical conditions. 

Lead author of the published paper, Dr. Micheala Kirschener from the Asbestos Diseases Research Institute in Sydney, Australia, stated that “if doctors could use a diagnostic marker based on a simple blood test to help with diagnosis, it could circumvent the problem of availability of tumor tissue and help to accelerate the diagnostic process."

Not only would this new mesothelioma test be quicker and cheaper, it would be less invasive as well.  Currently, biopsies must be taken and tissue samples analyzed to confirm or deny the presence of mesothelioma.  The process is expensive and patients have to undergo minor surgeries which could potentially have adverse side effects including infection.

The research was inspired by recent breakthroughs in the study of protein markers associated with mesothelioma cells.  Doctors have discovered that by determining the levels of certain proteins within the blood stream they can make a tentative diagnosis as to whether mesothelioma may be behind a patient’s illness.  However, this research is still considered experimental and is not without its flaws.  In fact, none of these proposed tests has yet reached the accuracy needed to be adopted for regular diagnostic use. 

MicroRNAs might provide an alternative diagnostic tool with a much higher accuracy rating.

MicroRNAs are short ribonucleic acids (similar to DNA) that function as post-transcriptional regulators.  In essence, these pieces of genetic code bind to complementary sequences on target messenger RNA and tell cells which genes to express and which to suppress. 

In this new line of research Dr. Kirschner and her associates examined 5 patients suffering from malignant pleural mesothelioma.  They compared certain test results to 3 healthy samples and identified 17 different microRNAs that significantly differed in concentration between the two groups.  Given the difference, they expanded their sample group to encompass 15 mesothelioma patients and compared their test results to 13 healthy individuals. 

The researchers zeroed in on a specific MicroRNA called miR-625-3p.  They found that that particular microRNA appeared at levels four times higher in the blood of patients with mesothelioma than in samples from healthy patients. 

Devising a simple test from the results, Dr. Kirschner was able to identify the presence of mesothelioma from a patient’s blood sample alone with an accuracy rating of 82.4%.

Kirschner was excited by these results and noted that this particular microRNA "performs as well as any previously proposed protein marker for detecting mesothelioma.”  However, she’s quick to caution that "like most diagnostic markers, miR-625-3p is not 100% accurate, and therefore there is a chance the assay will produce both false positives as well as false negatives.” 

The published study concluded with a call for further research into microRNAs in general and miR-625-3p specifically in order to determine if a higher accuracy rate could be achieved. 

If such a blood test could be devised, patients could more easily be screened for mesothelioma, including those who have been exposed to asbestos but aren’t yet presenting symptoms.  That would allow doctors an unprecedented opportunity to combat the disease at its earliest stages.