Key Takeaways
- Calretinin and mesothelin are two biomarkers that can be measured through blood tests to help diagnose mesothelioma. On their own, neither is sufficient — but when analyzed together, they are significantly more accurate.
- Mesothelin (MSLN) is a surface protein produced in small amounts by healthy mesothelial cells. In mesothelioma, mesothelin is significantly elevated — serving as a proxy for unchecked cancer cell growth. However, it is also associated with other cancers, so elevated mesothelin alone cannot confirm mesothelioma.
- Calretinin is considered the “gold standard” diagnostic biomarker for mesothelioma. If a patient tests calretinin-negative, it is generally assumed they do not have mesothelioma. A 2015 study showed calretinin could distinguish mesothelioma from carcinoma with significant accuracy.
- A 10-year longitudinal study (2008–2018) of 2,769 patients with non-fatal asbestos-related diseases found that mesothelin and calretinin analyzed together were the two most credible biomarkers for predicting an eventual mesothelioma diagnosis.
- These non-invasive blood-based tests could reduce the need for biopsies and extensive imaging in diagnosing mesothelioma — enabling earlier detection and faster treatment.
What is Mesothelin?
Mesothelin, or MSLN, is an established biomarker for mesothelioma among other cancers of
mesothelial tissue. MSLN is a surface-protein that is produced in trace amounts by healthy
mesothelial cells; in the case of mesothelioma, MSLN is significantly upregulated and is a proxy
for unchecked cellular growth and cancer aggression. Scientists and doctors have known about
elevated MSLN indicating mesothelioma for decades. But, because mesothelin is associated with
cancers beyond mesothelioma, and given mesothelioma’s relative rarity, mesothelin isn’t usually
checked in patients presenting with mesothelioma symptoms. There has to be another form of
diagnosing mesothelioma, like biopsy or extensive imaging, to justify elevated mesothelin as related to
mesothelioma.
What is Calretinin?
Calretinin, like mesothelin, is a well-known biomarker for malignant mesothelioma. One study
published in 2015 investigated the efficacy of calretinin quantities in differentiating
mesothelioma from carcinoma with the presence of effusions. The researchers found that they
were able to distinguish between carcinoma and mesothelioma with significant accuracy based
on calretinin alone. As a general rule of thumb, doctors use calretinin as the “gold standard” of
diagnostic biomarkers: if a patient tests calretinin-negative, it’s assumed that they don’t have
mesothelioma. Much like mesothelin, though, a calretinin-positive result isn’t sufficient as a
stand-alone proxy of mesothelioma.
Case Studies – Diagnosing Mesothelioma
A study conducted over the span of ten years–2008 to 2018–recorded biomarker levels in 2,769
patients that had non-fatal asbestos-related diseases. They found that mesothelin and calretinin,
as analyzed in conjunction, were the two most credible biomarkers for an eventual mesothelioma
diagnosis. The researchers were able to gauge the likelihood of non-fatal disease manifesting as
mesothelioma based on the patient’s changing calretinin and mesothelin levels. Because the
study was longitudinal, or took several years to complete, the results can’t be chalked up to
chance or error. And, because the participants were known to be exposed to asbestos, the
researchers opened up a potential link between asbestos fibers and calretinin/mesothelin levels.
Further research needs to be conducted before any conclusions can be made.
Implications for Diagnosing Mesothelioma?
Calretinin and mesothelin levels, when analyzed together, are credible indicators of
mesothelioma. Mesothelioma is notorious for its difficulty to be diagnosed because of a.) its
presentation that’s similar to other cancers; b.) its relationship to asbestos exposure; and c.) its
tendency to metastasize. If non-invasive techniques to diagnose–like testing calretinin and
mesothelin levels–aid in an early diagnosis, then they should be employed immediately.
Hopefully, calretinin and mesothelin-based proxies will become a standard when a patient
presents with mesothelioma-like symptoms. New research is changing the landscape of
diagnostic models, mesothelioma included.
If you or a loved one has been diagnosed with mesothelioma, please call 1 (800)-505-6000 or fill out our form. We are here to help you navigate the legal process of filing a claim to receive compensation for your mesothelioma diagnosis. We help mesothelioma victims and their families in Pennsylvania.
Frequently Asked Questions
What are calretinin and mesothelin?
Both are biomarkers — measurable substances in the body that can indicate the presence of disease:
- Mesothelin (MSLN) is a surface protein normally produced in trace amounts by healthy mesothelial cells. When mesothelioma develops, mesothelin levels become significantly elevated.
- Calretinin is a calcium-binding protein that is present in nearly all mesothelioma cases and is considered the “gold standard” biomarker for distinguishing mesothelioma from other cancers.
Both can be detected through blood tests, making them non-invasive diagnostic tools.
Can these biomarkers diagnose mesothelioma on their own?
Not individually. Mesothelin is elevated in several types of cancer beyond mesothelioma, so elevated levels alone don’t confirm the diagnosis. Calretinin is more specific to mesothelioma — a calretinin-negative result generally rules out the disease — but a positive result still isn’t considered sufficient on its own. However, when both biomarkers are analyzed together, their combined accuracy is significantly higher, potentially reducing the need for invasive biopsies and extensive imaging.
What did the 10-year longitudinal study find?
A study conducted from 2008 to 2018 tracked biomarker levels in 2,769 patients who had non-fatal asbestos-related diseases. Researchers found that mesothelin and calretinin, when analyzed together, were the two most credible biomarkers for predicting which patients would eventually develop mesothelioma. By monitoring changes in both biomarkers over time, researchers could gauge the likelihood of a patient’s non-fatal asbestos condition progressing to mesothelioma — a finding with major implications for early detection and screening.
Why is calretinin considered the “gold standard” for mesothelioma diagnosis?
Calretinin has earned this status because of its high sensitivity and specificity for mesothelioma. A 2015 study demonstrated that calretinin levels could distinguish between mesothelioma and carcinoma (another type of cancer) with significant accuracy, even in the presence of effusions (fluid buildup). The general diagnostic rule is: if a patient tests calretinin-negative, mesothelioma is effectively ruled out. This makes it an extremely valuable first-line screening tool.
Could these biomarkers replace biopsies for diagnosing mesothelioma?
Not yet — but they could significantly reduce the need for invasive procedures. Currently, a tissue biopsy remains the definitive way to confirm mesothelioma. However, if future research validates using calretinin and mesothelin together as a reliable screening tool, doctors could identify likely mesothelioma cases through a simple blood draw — reserving biopsies for confirmation rather than initial diagnosis. This would mean faster diagnoses, less patient discomfort, and lower healthcare costs.
How do these biomarkers relate to MESOMARK and other blood tests?
MESOMARK — the only FDA-approved blood test for mesothelioma — specifically tests for soluble mesothelin-related peptides (SMRPs), which are closely related to mesothelin. Calretinin is tested through a separate blood analysis. Other biomarkers being researched include fibulin-3 (present in mesothelioma but not other asbestos diseases), osteopontin (elevated in pleural mesothelioma), and CEA (absent in mesothelioma, helping distinguish it from lung cancer). The long-term goal is to develop a comprehensive blood-based screening panel that combines multiple biomarkers for maximum diagnostic accuracy.
Could these biomarkers help screen people with known asbestos exposure before they develop symptoms?
Potentially, yes. The 10-year longitudinal study specifically tracked patients who already had non-fatal asbestos-related diseases and used biomarker changes over time to predict which patients would eventually develop mesothelioma. If this approach is validated further, it could lead to routine biomarker screening for people with known asbestos exposure histories — enabling early detection before symptoms appear, which would dramatically expand treatment options and improve prognosis.
What should I do if I have a history of asbestos exposure?
If you have a history of asbestos exposure, inform your doctor and ask about available screening options — including blood tests for biomarkers like mesothelin and calretinin. Early detection is critical for expanding treatment options. If you or a loved one has been diagnosed with mesothelioma, call (800) 505-6000 or fill out our contact form for a free consultation.
