Mesothelioma Blood Test

While imaging tests and tissue biopsies are the most common methods for diagnosing mesothelioma, blood tests can also help doctors identify the disease. Mesothelioma blood tests look for certain indicators of disease, known as biomarkers, in a patient’s blood.
Although the broadest definition of biomarker also includes the measurement of physiological and anatomical criteria, for mesothelioma blood tests the term refers to measuring the levels of biological molecules associated with the disease, such as specific proteins or genes. If these biomarkers are detected in the blood in abnormally high concentrations, it may suggest a mesothelioma diagnosis.

In addition to their diagnostic benefits, biomarkers can also be used to predict the progression and aggressiveness of a patient’s mesothelioma. This can affect a patient’s mesothelioma prognosis and help doctors identify the patients who will respond best to certain treatments.
The MESOMARK assay is the most well-known blood test for mesothelioma. This FDA-approved test was the world’s first blood serum-based test sensitive for the disease. The MESOMARK kit scans a patient’s blood for levels of soluble mesothelin-related peptide (SMRP), a protein released into the blood by cancerous mesothelial cells.
Other blood tests can scan a patient’s blood for the mesothelioma biomarkers osteopontin and megakaryocyte potentiating factor (MPF). However, these tests are less readily available, and doctors still do not consider them accurate enough to replace histology as the gold standard for mesothelioma diagnosis.

Mesothelioma Guide

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MESOMARK Assay

Fast Fact

In a study of 1,086 blood samples, 99 percent of the healthy specimens displayed SMRP levels at or below the reference value used to indicate the presence of mesothelioma.

The MESOMARK assay measures the quantity of SMRP in a patient’s blood serum. Abnormally high SMRP levels may indicate the presence of mesothelioma, sometimes years before a mesothelioma diagnosis is made. However, because some types of mesothelioma tumors do not release SMRP (such as sarcomatoid mesothelioma), the FDA recommends that doctors combine the MESOMARK assay with other tests to ensure an accurate diagnosis.

Other diseases that can elevate SMRP levels include:
Ovarian cancer	Pancreatic Cancer	Lung Cancer	Pulmonary Carcinoma

MESOMARK can also help doctors track the progression of a mesothelioma tumor. In most cases, SMRP levels increase as the disease progresses. In one study, 10 out of 18 mesothelioma patients whose imaging scans indicated progressive disease also displayed an SMRP level increase of at least 30 percent on a follow-up MESOMARK assay.

The MESOMARK Assay Procedure

The MESOMARK assay is completed in two steps. First, the doctor takes two small blood samples from the patient’s vein. Each sample contains about two teaspoons of blood. The doctor then sends the samples to a laboratory for official analysis. The patient is free to go home after the procedure, and is generally not at risk for any significant side effects.
At the laboratory, technicians add several antibodies to the blood samples that bind to the protein fragments. They then stir the mixture and place it in a laboratory instrument called a plate reader. Computer software analyzes the contents of the blood sample and provides a measurement of the amount of SMRP-bound antibodies present.

SMRP levels at or above a certain reference point may suggest the presence mesothelioma or another malignant pleural disease. Elevated SMRP levels can also be used to identify asbestos-exposed individuals who do not yet have mesothelioma. This implies that blood tests could someday serve as a screening tool for patients at high risk for developing mesothelioma in the future, but most studies suggest the results are not yet reliable enough.
In one study of 40 subjects with a history of asbestos exposure, seven individuals displayed elevated SMRP levels. Within five years of the blood test, three of these patients were diagnosed with mesothelioma. None of the 33 patients with normal SMRP levels developed mesothelioma in the next eight years.

Other Biomarker-Based Mesothelioma Blood Tests

Some other laboratory blood tests screen a patient for osteopontin and megakaryocyte potentiation factor (MPF). Levels of these biomarkers are also significantly higher in the blood of mesothelioma patients compared to healthy individuals or patients with other cancers. Laboratory technicians measure these biomarkers in the blood with a method known as enzyme-linked immunoabsorbent assay (ELISA).
Osteopontin and MPF blood tests are not quite dependable enough to make an official mesothelioma diagnosis. Osteopontin and MPF lack specificity as diagnostic markers, meaning there is not a high enough likelihood that a positive test result truly indicates a patient has mesothelioma. However, the blood tests that rely on these biomarkers can play a significant role in monitoring the disease.

Human Osteopontin ELISA Kit from R&D Systems

Osteopontin is a type of protein that controls cell adhesion and bone-matrix interactions. Levels of this protein are elevated in mesothelioma patients – even when compared to patients with benign asbestos-related conditions like asbestosis and pleural thickening. As a result, osteopontin is a reliable biomarker for differentiating between healthy asbestos-exposed individuals and those who have developed mesothelioma. Some studies suggest that osteopontin blood tests can even reflect the duration of a patient’s asbestos exposure.

Other diseases that can elevate osteopontinlevels include:
Lung cancer	Colon Cancer	Breast cancer	Tuberculosis

In a study exploring the potential uses for mesothelioma biomarkers, osteopontin was the only blood-based biomarker unable to differentiate malignant mesothelioma from other cancers. However, it did prove useful for screening asbestos-exposed populations, monitoring treatment and predicting prognosis.
In one study, patients with a high serum osteopontin level experienced significantly shorter survival rates than patients with low serum osteopontin levels. Patients with more than 350 nanograms of osteopontin per milliliter of serum had a median survival of five months, while patients below this threshold had a median survival of 15 months.

Human Megakaryocyte Potentiation Factory (MPF) ELISA kit

Blood analysis tests can also identify the presence of megakaryocyte potentiation factor (MPF), a soluble protein produced by another mesothelin precursor protein. Doctors do not fully understand the biological function of MPF, but they do know it is released into the bloodstream of mesothelioma patients in extremely high quantities.
In one small study, laboratory technicians identified MPF in the blood serum of 91 percent of late-stage mesothelioma patients. They did not detect MPF in the blood of healthy donors.

Other diseases that can produce elevated MPF levels:
Ovarian cancer	Pancreatic cancer

In the same study, researchers measured the MPF levels of four patients before and after mesothelioma debulking surgery. In two of the patients, MPF levels decreased immediately after surgery. In one patient, surgeons could only remove 10 percent of the tumor, and post-surgical MPF levels did not significantly change. This indicates that MPF blood testing can help monitor a mesothelioma patient’s response to surgery.
While mesothelioma blood tests show great potential for diagnosing the disease and predicting its outcome, researchers are working diligently to improve the reliability of their results. These tests could one day provide doctors with a low-cost, minimally invasive method for diagnosing mesothelioma, but only after  researchers uncover ways to improve their sensitivity.