Mesothelioma Diagnosis

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A mesothelioma diagnosis may involve imaging scans of tumors, blood tests and a biopsy of suspected cancerous tissue. A biopsy is the only mesothelioma test that confirms a diagnosis. Signs and symptoms of mesothelioma can include shortness of breath and chest pain. Misdiagnosis of mesothelioma is common, so telling your doctor about known asbestos exposure is important.

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Leading mesothelioma oncologist Dr. David Sugarbaker explains how mesothelioma cancer is diagnosed.
Leading mesothelioma oncologist Dr. David Sugarbaker explains how mesothelioma cancer is diagnosed.

What Steps Lead to a Mesothelioma Diagnosis?

  1. Symptoms: Symptoms of mesothelioma cause the patient to visit their primary care physician or a hospital for testing.
  2. Mesothelioma Testing: Tests reveal abnormal results, which leads to further testing and referral to an oncologist.
  3. Confirm Diagnosis: The oncologist uses imaging scans, blood tests and biopsies to confirm a mesothelioma diagnosis.

There is no clear path to a mesothelioma cancer diagnosis for every patient.

Because the disease is rare and has symptoms associated with less serious conditions, doctors sometimes confuse it for a different illness or another type of cancer. It is common for patients to be misdiagnosed with several conditions before receiving a mesothelioma diagnosis.

Providing your doctor with a comprehensive work history is important to the diagnostic process. Doctors are unlikely to suspect the disease unless a patient describes a former job where asbestos exposure may have occurred.

How to Test for Mesothelioma

Mesothelioma testing commonly includes imaging scans, biopsies and blood tests. Imaging scans like X-rays and CT scans identify mesothelioma tumors. A biopsy is the only definitive way to confirm a mesothelioma diagnosis. Mesothelioma blood tests are used to measure treatment response.

Imaging tests reveal the size and location of mesothelioma tumors. The “gold standard” for mesothelioma imaging is a combination CT-PET scan.

Imaging Tests Commonly Used in Mesothelioma Diagnosis

  • X-Rays: Produce basic images of dense areas, such as tumors, within the body
  • CT Scans: Use electromagnetic imagery to create detailed images of internal structures
  • MRIs: Generate images of highly active internal structures using magnets and radio waves
  • PET Scans: Highlight areas of the body that have abnormally high, potentially cancerous metabolic activity

Mesothelioma Biopsies

Biopsies are the only way to confirm a mesothelioma diagnosis. The most accurate biopsy technique for mesothelioma is called a thoracoscopy.

  • Thoracoscopy: Takes samples with a camera-equipped tube that doctors insert through the chest wall.
  • Mediastinoscopy: Mediastinoscopies are similar to thoracoscopies, except doctors insert the tube through an incision in the neck.
  • Thoracentesis: Removes pleural fluid buildup around the lungs to help diagnose the cause of pleural effusions.
  • Fine-Needle Aspiration: Extracts cells through a thin, hollow needle and a syringe.

Mesothelioma Blood Tests and Biomarkers

Mesothelioma blood tests and biomarkers are not accurate enough to diagnose the cancer alone. They are helpful at monitoring response to treatment. 

  • MESOMARK: This FDA-approved test can detect soluble mesothelin-related peptide. 
  • SOMAmer: This test can detect more than 1,000 proteins in blood serum. These proteins may have diagnostic value in identifying mesothelioma. 
  • Human MPF: This test measures a protein called megakaryocyte potentiation factor. 
Diagnostic Capabilities of Mesothelioma Blood Tests
Test Sensitivity 1 Specificity 2
MESOMARK 68% 92%
SOMAmer 90% 95%
Human MPF 68% 95%
  1. The percentage of mesothelioma patients correctly diagnosed by the test.
  2. The percentage of healthy people in which the test correctly ruled out a mesothelioma diagnosis.
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How to Prepare for Mesothelioma Diagnostic Appointments

  • Assemble all necessary documents, including insurance cards and ID.
  • Make sure to discuss any asbestos exposure you may have experienced including length, time and location of exposure.
  • Bring a summary of your medical history, including details about your recent symptoms, and a list of current medications.
  • Bring something to take notes during the appointment.
  • Gather a list of questions you have for your medical team.
  • Ask a friend or family member to join you for support and assistance.

How to Prepare for a Diagnostic Imaging Scan

  • You may have a light meal or snack four hours before the scan, then no food or drink by mouth. However, some scans require eight hours of fasting.
  • Take medications as usual, unless instructed otherwise.
  • Ask your doctor if your scan requires consuming liquid oral contrast before the scan and plan accordingly.
  • Research relaxation techniques if you are nervous about being in an enclosed scanning machine.
  • Plan to spend up to several hours at the appointment.
  • You’ll get the results from your doctor within one to two weeks of the appointment.

How to Prepare for a Biopsy

  • Do not eat or drink anything four hours before your appointment.
  • Stop taking any blood thinning medication at least five days before a biopsy.
  • Wear loose clothing to the appointment.
  • Have a designated driver take you home.
  • Plan to spend several hours undergoing the biopsy and about three days at the hospital to fully recover.
  • You may have to wait two to three days to get the results.

How to Prepare for a Blood Test

  • Ask how long you must fast before the blood test. Some tests require you to not eat after midnight the night before your appointment.
  • Book an early-morning appointment if you have to fast for the test.
  • Drink plenty of water, which prevents your blood pressure from dropping.
  • Plan to spend about 30 minutes at the appointment.

Depending upon the test, you may receive results instantly or within a week.

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Timeline of the Diagnostic Process for Mesothelioma

Day 1:
Initial symptoms such as shortness of breath, fatigue and chest pain are common. It’s not diagnosed at that time, but the doctor might order X-rays.
Day 2:
X-rays determine fluid in the lungs could be pneumonia.
Day 3-Day 13:
Physician prescribes antibiotic to treat pneumonia (10-day treatment) or drains fluid in pleural cavity. No cancer cells detected in fluid.
Day 14:
X-rays after treatment show lungs are clear. Doctor orders follow-up X-rays and asks patient to return in 30 days.
Day 44:
Follow-up X-rays show fluid buildup in pleural cavity again. Doctor either drains fluid, which may again test negative for cancer cells, or treats the pneumonia with antibiotics again (add 10 days). Doctor orders PET scans and CT scans.
Day 54:
Imaging scans show a possible underlying cause or recurrent pneumonia. Patient is referred to a surgeon for an appointment, which can take up to 15 days.
Day 69:
Surgeon schedules a biopsy appointment, which can take up to 10 days.
Day 79:
Surgeon takes biopsy, usually done with video-assisted thoracoscopic surgery. The procedure, known as VATS, uses a thin fiber-optic tube to enter the chest cavity and take biopsy samples. This typically requires a three-day hospital stay for the patient. Pathology work on mesothelioma tests can take up to 10 days if surgeon sends biopsy to an outside lab.
Day 89:
(Approximately three months later): Mesothelioma confirmed if biopsy tests positive for the disease.

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Challenges in Diagnosing Mesothelioma

Staging Mesothelioma

Staging mesothelioma is an important but challenging part of the diagnostic process. Staging defines how far the cancer has progressed, which is the biggest factor in determining which treatments are right for a patient.

Cancer stage is also a primary factor influencing a mesothelioma patient’s life expectancy.

The challenge with staging mesothelioma is that it’s hard to do accurately without invasive surgery.

  • Clinical staging uses imaging scans and biopsies to estimate the stage. Imaging tests are the most noninvasive tools doctors have for estimating the stage of mesothelioma. Biopsies, such as a thoracoscopy and mediastinoscopy, are minimally invasive and they can help determine if the cancer has spread beyond the pleural lining or into lymph nodes.

  • Surgical staging directly examines tumor spread to precisely determine the stage.

Unfortunately, surgery is an invasive procedure and can’t be performed on patients who are in poor health or have late-stage mesothelioma. Imaging scans and biopsies work well enough to identify late-stage tumor spread. This precludes patients from surgery because the cancer has grown to the point that surgical removal becomes life-threatening.


Sometimes mesothelioma is misdiagnosed as a less serious disease or another cancer. The initial symptoms of mesothelioma can resemble other conditions.

  • Pleural mesothelioma symptoms may lead to a diagnosis of pneumonia.
  • Peritoneal mesothelioma symptoms may lead to a diagnosis of irritable bowel syndrome.
  • Pericardial mesothelioma symptoms may lead to a diagnosis of coronary heart disease.

It can also be misdiagnosed as other forms of cancer.

  • Pleural mesothelioma may be misdiagnosed as a form of lung cancer that develops in mucus-secreting glands called adenocarcinoma.
  • Peritoneal mesothelioma may be misdiagnosed as ovarian cancer or colon cancer.

Working with a cancer center that specializes in mesothelioma can confirm or deny the diagnosis. The professionals working at these centers have the experience necessary to accurately diagnose the disease.

Quick Fact:

In a cytology, a doctor removes some fluid from the suspected tumor site. A pathologist then looks at the fluid under a microscope to search for cancer cells. In a biopsy, a doctor takes a tissue sample of the suspected tumor, so a pathologist can look at it under a microscope to determine if it is cancerous.

Lorraine Kember, a former mesothelioma caregiver, describes how she felt when her husband tested positive for mesothelioma.

Latency Period

The decades-long latency period associated with asbestos-related diseases means that some patients forget they were exposed to asbestos a long time ago. They don’t mention their history of asbestos exposure, and consequently, their doctor doesn’t consider mesothelioma as a possible diagnosis.

This may contribute to a delay in diagnosis, allowing the cancer to progress without proper treatment.


When a doctor delivers a mesothelioma diagnosis, a prognosis might also be offered to the patient.

It is challenging for doctors to accurately predict the course mesothelioma will take in a patient’s body because each case is truly unique. Doctors base their prognosis on the cancer’s stage, location and cell type in addition to the patient’s age and overall health.

Some doctors chose to wait for the patient to ask about their prognosis, while others offer the prognosis right away.

Steps to Take After a Mesothelioma Diagnosis

Seek a Second Opinion

The next step after a mesothelioma diagnosis for many people is seeking a second opinion from a mesothelioma specialist. Choosing a doctor and cancer center that specializes in mesothelioma can confirm the diagnosis and get you access to innovative therapies and clinical trials.

Understand Your Treatment Plan

Another important step is thoroughly understanding your treatment plan. This is something you can discuss in detail with your oncologist. If there is any aspect of your treatment plan that makes you nervous or confused, talk to your doctor about it.

Ask about palliative care and complementary therapies that may help with side effects. For example, acupressure may help with chemotherapy-induced nausea.

Get Support

Lastly, build a mesothelioma support network to help you and your loved ones cope with this cancer. Reach out to family, friends, neighbors and community members. A strong support system will help you get through the challenges of a being diagnosed with mesothelioma.

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Registered Nurse and Patient Advocate

Karen Selby joined in 2009. She is a registered nurse with a background in oncology and thoracic surgery and was the regional director of a tissue bank before becoming a Patient Advocate at The Mesothelioma Center. Karen has assisted surgeons with thoracic surgeries such as lung resections, lung transplants, pneumonectomies, pleurectomies and wedge resections. She is also a member of the Academy of Oncology Nurse & Patient Navigators.

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Last Modified June 20, 2019

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