Blood Tests for Mesothelioma
Blood tests measuring specific biomarkers can support mesothelioma diagnosis and monitoring, but cannot provide a definitive diagnosis alone. Tissue biopsy remains the gold standard.
What biomarkers do:
- Help indicate possible mesothelioma presence
- Monitor disease progression
- Track treatment response
- Assist with prognosis
Key Mesothelioma Biomarkers
Soluble Mesothelin-Related Peptides (SMRP)
SMRP is the most commonly used blood biomarker for mesothelioma.
The MESOMARK Assay:
- FDA-approved in 2007
- Detects elevated SMRP levels released by mesothelioma cells
- Particularly effective for epithelioid subtype
- Less effective for sarcomatoid mesothelioma
Uses:
- Monitoring disease extent
- Tracking treatment response
- Assisting with prognosis
- Supporting (not confirming) diagnosis
Mesothelin
Mesothelin is a protein that is:
- Expressed at low levels in normal cells
- Highly elevated in pleural mesothelioma
- One of the most studied mesothelioma biomarkers
Limitations:
- Can be elevated in other cancers (ovarian, pancreatic)
- No single biomarker is sufficient for diagnosis
- Best used in combination with other markers
Fibulin-3
An emerging biomarker under investigation:
- Shows promise in distinguishing malignant from benign pleural effusions
- May complement mesothelin testing
- Research ongoing for clinical utility
CA-125
While not mesothelioma-specific:
- Can help assess disease burden
- Useful for tracking progression
- Often used alongside other markers
Biomarkers in Clinical Practice
Current Uses
| Use Case | Role of Biomarkers |
|---|---|
| Initial workup | Support clinical suspicion, guide further testing |
| Disease monitoring | Track changes over time |
| Treatment response | Assess if therapy is working |
| Prognosis | Higher levels may indicate worse outcomes |
| Recurrence detection | May rise before imaging shows progression |
How Blood Tests Fit in Diagnosis
Blood tests are used alongside other diagnostic tools:
- Initial suspicion: Symptoms + exposure history
- Imaging: CT, PET scans reveal abnormalities
- Biomarkers: Blood tests indicate possible mesothelioma
- Biopsy: Tissue sample confirms diagnosis
- Immunohistochemistry: Staining confirms cell type
Diagnostic Sensitivity
| Test Type | Sensitivity |
|---|---|
| Pleural fluid cytology | 40-90% |
| SMRP blood test | Variable, higher in epithelioid |
| Tissue biopsy with IHC | Highest (gold standard) |
Limitations of Blood Tests
Why Biomarkers Can’t Diagnose Alone
- False positives: Elevated levels can occur in other conditions
- False negatives: Some mesotheliomas don’t produce high levels
- Subtype variation: Sarcomatoid tumors may not elevate SMRP
- Specificity issues: Other cancers can elevate same markers
What Blood Tests Cannot Tell You
- Definitive mesothelioma diagnosis
- Exact tumor location or stage
- Cell type (epithelioid, sarcomatoid, biphasic)
- Whether you’ll develop mesothelioma (in exposed individuals)
Early Detection Research
Current Status
- No routine screening exists for asbestos-exposed populations
- Blood tests are being studied for early detection
- Multi-biomarker panels show more promise than single markers
- AI integration being explored for better interpretation
Promising Approaches
Multi-biomarker panels:
- Combining mesothelin + fibulin-3 + other markers
- Improves sensitivity and specificity
- Under investigation in clinical trials
Circulating tumor DNA (ctDNA):
- Detects cancer DNA fragments in blood
- May enable earlier detection than protein biomarkers
- Research ongoing for mesothelioma application
Challenges for Screening
For a screening test to be useful, it must:
- Detect disease early enough to improve outcomes
- Have high sensitivity (catch most cases)
- Have high specificity (few false positives)
- Be practical and cost-effective
Current biomarkers don’t yet meet all criteria for population screening in asbestos-exposed individuals. Research into multi-biomarker panels and circulating tumor DNA continues.
When Biomarkers Are Ordered
During Initial Workup
Your doctor may order biomarker testing if:
- Imaging shows pleural abnormalities
- You have symptoms consistent with mesothelioma
- You have a history of asbestos exposure
For Monitoring
Regular biomarker testing may be used to:
- Track disease during treatment
- Detect early signs of progression
- Monitor for recurrence after treatment
Typical Testing Schedule
During treatment or surveillance:
- Every 3-6 months initially
- Frequency adjusted based on individual situation
- Often coordinated with imaging
Understanding Your Results
What Elevated SMRP Means
- Suggests possible mesothelioma (but doesn’t confirm it)
- Higher levels may correlate with greater disease burden
- Rising levels may indicate disease progression
What Normal SMRP Means
- Doesn’t rule out mesothelioma
- Some mesotheliomas don’t produce high SMRP
- Other testing still needed if clinical suspicion exists
Immunohistochemistry: The Diagnostic Standard
When tissue is obtained, pathologists use immunohistochemistry (IHC) staining to confirm mesothelioma:
Markers supporting mesothelioma:
- Calretinin (positive)
- WT-1 (positive)
- D2-40 (positive)
- CK5/6 (positive)
Markers ruling out other cancers:
- CEA (negative in mesothelioma)
- TTF-1 (negative in mesothelioma)
- MOC-31 (negative in mesothelioma)
What biomarker tests are appropriate for my situation?▼
SMRP (MESOMARK) is most commonly used, particularly for epithelioid mesothelioma. Your doctor may also order mesothelin, fibulin-3, or CA-125 depending on your case and what’s being monitored.
How will these results affect my diagnosis or treatment?▼
Biomarkers support diagnosis but can’t confirm it alone—biopsy is required. During treatment, rising or falling levels help indicate whether therapy is working. Results guide decisions but don’t replace imaging or clinical assessment.
How often should biomarkers be monitored?▼
Typically every 3-6 months during treatment or surveillance, often coordinated with imaging. Frequency is adjusted based on your individual situation and treatment response.
What do my current biomarker levels indicate?▼
Elevated SMRP suggests possible mesothelioma but doesn’t confirm it. Higher levels may correlate with greater disease burden. Normal levels don’t rule out mesothelioma—some tumors don’t produce high SMRP.
References
Journal of Thoracic Disease. (2018). Mesothelin as a biomarker for malignant mesothelioma.
https://pubmed.ncbi.nlm.nih.gov/29268361/
Current Opinion in Pulmonary Medicine. (2008). Soluble mesothelin-related peptides in mesothelioma.
https://pubmed.ncbi.nlm.nih.gov/18043273/
Annals of Translational Medicine. (2017). Biomarkers in the diagnosis of malignant pleural mesothelioma.
https://pubmed.ncbi.nlm.nih.gov/28251126/