Mesothelioma Blood Tests & Biomarkers

Blood tests and biomarkers are an evolving component of mesothelioma diagnosis and management. While no blood test can definitively diagnose mesothelioma on its own, several serum biomarkers have been identified that can support the diagnostic process, monitor treatment response, and detect disease recurrence. The most established biomarker is soluble mesothelin-related peptide (SMRP), measured by the FDA-approved MESOMARK assay.¹

Mesothelin is a protein normally expressed on the surface of mesothelial cells lining the pleura, peritoneum, and pericardium. In mesothelioma, mesothelin is often overexpressed, and a soluble fragment (SMRP) is released into the bloodstream at elevated levels. The MESOMARK assay, approved by the FDA in 2007, measures SMRP levels in blood serum. Elevated SMRP levels are found in approximately 60–80% of epithelioid mesothelioma patients, though sensitivity is lower for sarcomatoid subtypes.²

Additional biomarkers under investigation include fibulin-3, a glycoprotein found at elevated levels in plasma and pleural effusions of mesothelioma patients; high-mobility group box 1 (HMGB1), a nuclear protein released by damaged mesothelial cells; and osteopontin, a glycoprotein involved in cell signaling and immune function. Research combining multiple biomarkers into panel assays has shown improved diagnostic accuracy compared to individual markers alone.³

It is critical to understand the limitations of current mesothelioma biomarkers. No single blood test has sufficient sensitivity and specificity to serve as a standalone diagnostic or screening tool. SMRP can be elevated in other conditions including ovarian cancer, pancreatic cancer, and renal failure, and it may be normal in up to 40% of mesothelioma cases. Tissue biopsy with immunohistochemical analysis remains the gold standard for definitive diagnosis. Patients concerned about mesothelioma should pursue comprehensive diagnostic evaluation and consult with a mesothelioma attorney about their legal options.

The primary mesothelioma blood biomarkers and their clinical applications include:

• Soluble mesothelin-related peptide (SMRP) — the most validated biomarker; elevated in 60–80% of epithelioid mesothelioma cases; measured by the MESOMARK assay; useful for monitoring treatment response and detecting recurrence
• Fibulin-3 — elevated in plasma and pleural effusions; may complement SMRP for improved diagnostic accuracy; still under investigation for clinical utility
• HMGB1 (high-mobility group box 1) — released by damaged mesothelial cells exposed to asbestos; hyperacetylated HMGB1 may distinguish mesothelioma from asbestos exposure without cancer
• Osteopontin — elevated in mesothelioma but also in many other cancers and inflammatory conditions; limited specificity
• Megakaryocyte potentiating factor (MPF) — released alongside mesothelin; may complement SMRP measurements

Biomarker panels combining two or more markers show improved sensitivity and specificity compared to individual tests. However, tissue biopsy remains essential for definitive diagnosis.³

Blood biomarkers have prognostic as well as diagnostic value:

• Higher baseline SMRP levels have been associated with more advanced disease and shorter survival in some studies
• Declining SMRP levels during treatment may indicate positive treatment response
• Rising SMRP levels after treatment may signal disease recurrence before imaging findings appear
• Fibulin-3 levels have shown correlation with disease stage and prognosis in preliminary studies