A calcium-binding protein called calretinin may provide the basis for a new kind of blood test for the asbestos-linked cancer, malignant mesothelioma.
Right now, there is no reliable way to detect the presence of a mesothelioma tumor before symptoms develop.
The Search for a Mesothelioma Blood Test
But scientists around the world are searching for ways to use certain compounds produced by tumors to diagnose mesothelioma earlier, allowing for earlier treatment and potentially better outcomes.
Calretinin is one such compound. It is a protein involved in calcium signaling, a process that governs a number of critical cellular processes.
A team of scientists from Germany and Australia recently pitted calretinin against the more established mesothelioma biomarker, mesothelin, in a test to see which protein offered the best chance of identifying the asbestos cancer early.
Testing Mesothelioma Biomarkers
The test involved 163 Australian men and 36 German men with malignant pleural mesothelioma. Another 163 Australians and 72 Germans who had non-malignant asbestos-associated conditions (asbestosis or pleural plaques) made up a control group.
Samples of blood serum and plasma had been collected from all the participants prior to therapy. These were tested for the presence of both calretinin and mesothelin.
Taking into consideration all the different factors that could potentially impact the concentrations of these markers in the blood, such as age, mesothelioma subtype, and how long their blood samples had been stored, the team estimated the diagnostic performance of both markers.
The Benefits and Limitations of Calretinin
The scientists found that the calretinin-based blood test was able to correctly identify cases of epithelioid or biphasic mesothelioma 71 percent of the time. That is comparable to mesothelin, which correctly identified 69 percent of these mesothelioma cases correctly.
The news was even better when the two types of markers were used together. In that case, calretinin increased the sensitivity of mesothelin from 66 percent to 75 percent. Just as importantly, the combination test was able to correctly rule out mesothelioma with 97 percent accuracy.
The only downside of calretinin appeared to be the fact that the biomarker’s effectiveness broke down when it came to identifying sarcomatoid mesothelioma, the rarest subtype.
“The assay [blood test[ is robust and shows a performance that is comparable to that of mesothelin,” writes lead author Georg Johnen, one of the developers of the calretinin-based blood test, in BMC Cancer. “Molecular markers like calretinin and mesothelin are promising tools to improve and supplement the diagnosis of malignant mesothelioma and warrant further validation in a prospective study.”
All subtypes of mesothelioma are caused by exposure to asbestos and are continuing to rise in the US, despite strict regulations. Because late-state mesothelioma rarely responds to conventional cancer treatments, earlier detection is key to improving survival rates.
Johnen, G, et al, “Calretinin as a blood-based biomarker for mesothelioma”, May 30, 2017, BMC Cancer,