Biomarkers are special substances in the bloodstream that may signal the presence of mesothelioma. Blood tests called “assays” can be used by doctors to detect these biomarkers and indicate the need for additional diagnostic tests.
Although biomarker assays cannot confirm a mesothelioma diagnosis on their own, they can be a useful tool for detecting mesothelioma earlier than other tests. Since early detection is the best way to improve prognosis, researchers continue working to find new blood tests – and improve existing ones – in an effort to catch the deadly disease before it spreads.
Mesothelioma Biomarker Quick Facts
- Biomarkers are unusual levels of substances in the blood or other bodily fluids (e.g., pleural fluid).
- Blood tests cannot diagnose mesothelioma on their own.
- Researchers are hopeful that biomarker assays can be improved to detect mesothelioma early.
- Such early detection is the best way to improve mesothelioma prognosis.
What Exactly Is a Mesothelioma Biomarker?
Cancer cells use nutrients at a faster rate than normal cells, which can lead to an excessive amount of cellular byproducts in the blood. These higher levels of byproducts are called biomarkers because they leave a different biological mark than normal cells.
For example, normal mesothelial cells produce a glycoprotein (sugar + protein molecule) called mesothelin. Malignant mesothelioma cells produce mesothelin as well, but in much higher quantities, in part due to their faster rates of growth. Several mesothelioma biomarker assays look for increased levels of mesothelin, or byproducts of mesothelin, as an indication that a mesothelioma tumor may exist.
How Effective Are Mesothelioma Blood Tests?
Currently, there are no biomarker assays that can have been approved for diagnosing mesothelioma on their own. At best, these blood tests can indicate the potential that a mesothelioma tumor exists, thus giving doctors a basis to perform further diagnostic procedures, such as a biopsy.
Nevertheless, there are some promising developments in recent clinical trials. For example, in one recent study a biomarker known as HMGB1 was able to distinguish between people who had mesothelioma, people who had been exposed to asbestos (but did not have mesothelioma), and people who had no known asbestos exposure.
Given such hopeful news, researchers are continuing to refine existing blood tests and look for new biomarkers that can detect mesothelioma early. If you or a loved one have been exposed to asbestos and are exhibiting mesothelioma symptoms, it may be worthwhile to connect with a mesothelioma expert to discuss the effectiveness of biomarker assays and other diagnostic tests.
What Biomarker Assays (Blood Tests) Exist for Mesothelioma?
Currently, only one biomarker assay has been approved by the U.S. Food & Drug Administration (FDA) for testing, although it is not sufficient to diagnose mesothelioma itself. In additional, there are several other tests that have been developed to detect mesothelioma with varying levels of accuracy and sensitivity.
MesoMark works by testing for high levels of soluble mesothelin-related peptides (SMRPs), which are fragments or variants of mesothelin – a substance produced in small quantities by healthy mesothelial cells, and in much higher quantities by mesothelioma cancer cells, especially in those who have pleural mesothelioma. These SMRPs are found in the serum part of the blood, though they can also be found in pleural fluid as well.
SMRP levels tend to be higher in individuals with Stage 3 or Stage 4 mesothelioma, and as a result the MesoMark assay is more accurate in those later stages of the disease. Overall, the sensitivity of the test ranges widely, from about 19 to 68 percent, making it insufficient to diagnose mesothelioma on its own.
HMGB1 (High Mobility Group Box Protein 1)
This relatively new biomarker assay is showing a lot of promise as a way to detect mesothelioma early. In a recently published study, researchers found that not only could different levels of HMGB1 distinguish between those who have mesothelioma and those who don’t – it could also differentiate between those who had been exposed to asbestos and those who have not!
HMGB1 has been used as a biomarker for other types of cancer, such non-small cell lung cancer (NSCLC). As a mesothelioma biomarker, HMGB1 could not only provide a way to detect the cancer, but also serve as a way to monitor asbestos exposure in general and serve as an indicator for risk factors of other asbestos-related diseases.
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One particular fragment of the glycoprotein mesothelin is known as N-ERC/mesothelin. In some studies, researchers have detected N-ERC/mesothelin in blood serum with a 95% rate of sensitivity – a very good accuracy rate, but not quite high enough to allow diagnosis on its own.
While this particular biomarker assay is extremely promising, additional testing is required before it could be used widely for mesothelioma diagnosis. Another potential use for the test would be to monitor mesothelioma patients after they receive chemotherapy treatments, to determine whether the mesothelioma had recurred.
Another glycoprotein that can be found in higher levels in individuals with certain types of cancer is osteopontin. In 2005, Dr. Harvey Pass and a team of colleagues showed that mesothelioma also produced glycoprotein at increased levels.
Although osteopontin may be a good indicator of whether a person is ill, it is poor at diagnosing mesothelioma specifically. This is due to the fact that osteopontin levels can increase not only due to cancer, but also due to other conditions, including kidney stones, ischemic stroke, and various inflammatory and autoimmune diseases.
Yet another glycoprotein produced by mesothelioma cells is fibulin-3. Early studies that tested for this substance showed great promise, with sensitivity levels as high as 97%. However, in recent studies, that high level of accuracy could not be substantiated, meaning that the test may be unsuitable for diagnostic purposes.
Even if a fibulin-3 test cannot diagnose mesothelioma, there may still be some beneficial uses for it. In particular, after a mesothelioma diagnosis, fibulin-3 could be used to help doctors track the progress of the cancer, as well as the effectiveness of treatment efforts. Fibulin-3 could also help doctors distinguish between malignant and benign diseases of the lungs and pleura.
Blood Test Costs
Because many of these blood tests are still experimental and unapproved for diagnosing mesothelioma, they may not be covered by insurance. Combined with the costs of other diagnostic tests, and the overall expenses that mesothelioma patients will incur during treatment, recovery and follow-up care, the amount that patients and their families have to pay will skyrocket over time.
However, there is some hope for individuals who have mesothelioma. Money from asbestos trust funds may be available, and there may be other financial options that mesothelioma patients can take advantage of. If you or a loved one have been diagnosed with mesothelioma, contact an expert who can help you understand your financial options and legal rights.Sources
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Wheatley-Price P, Yang B, Patsios D, et al. Soluble mesothelin-related peptide and osteopontin as markers of response in malignant mesothelioma. Journal of Clinical Oncology. July 2010;28(20):3316-3322. doi: 10.1200/JCO.2009.26.9944