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Mesothelioma Diagnosis

Doctors use diagnostic procedures such as imaging tests, blood-marker tests and biopsies in order to accurately diagnose pleural mesothelioma. Seeking care from a mesothelioma specialist is your best option to avoid a misdiagnosis.

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The diagnostic process for pleural mesothelioma incorporates numerous tests and requires the close cooperation of a diverse team of medical experts. While most patients first meet with a general practitioner, their diagnosis can involve the expertise of radiologists, surgeons, oncologists, pathologists, pulmonologists and others.

These additional specialists can be necessary because this form of cancer is so challenging to diagnose, even for highly qualified oncologists. Symptoms rarely appear until the disease has entered its later stages, and even then they are hard to distinguish from the signs of more common respiratory illnesses. Many patients with pleural mesothelioma don’t experience symptoms until the cancer is in later stages of development.

A diagnosis usually starts with a patient talking about symptoms and providing a medical and occupational background to a physician. The occupational part of the discussion is important. Pleural mesothelioma almost always stems from occupational exposure to asbestos. Doctors follow up with a physical exam.

If a patient describes one or more risk factors for pleural mesothelioma, such as past exposure to asbestos, additional tests will be required. These may include imaging scans, biopsies or blood tests.

Seeing a Mesothelioma Specialist

In the earliest stages of pleural mesothelioma, signs of disease are nonexistent or virtually undetectable. While bothersome symptoms compel most patients to schedule an initial consultation with their doctor, problems can be so mild that people ignore them at first. Because even medical experts can easily mistake initial mesothelioma symptoms for those of less serious conditions, delays in the diagnostic process of up to six months are commonplace.

A patient’s first appointment is usually with their primary care provider, who often refers the patient to a pulmonologist. Further testing with a pulmonologist leads to a referral with an oncologist, who then conducts advanced imaging and tissue sampling tests.

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Symptoms of Pleural Mesothelioma

In 90 percent of cases, shortness of breath is the first symptom of pleural mesothelioma. Many patients also complain of a cough or chest pain. When patients with these symptoms first schedule an appointment, the doctor starts by performing a medical history review. People with a history of asbestos exposure need to tell all doctors about their exposure history in great detail, which will allow physicians to quickly consider asbestos-related diseases like pleural mesothelioma.

During the review, the doctor considers the patient’s respiratory symptoms and should look for other signs of mesothelioma like fever, weight loss and difficulty breathing.

Next, the doctor performs a complete physical exam. The physical can check for areas of inflammation and signs of other health concerns. An X-ray may be ordered to help determine if the patient has pleural effusion, a buildup of fluid in the chest that can indicate a mesothelioma diagnosis. The fluid collects in a cavity between the lungs and pleura, a thin layer surrounding the lungs that aids in breathing.

Lastly, the patient will take pulmonary function tests (PFTs), which check how well the lungs are functioning. If the patient’s symptoms, medical history review and physical exams suggest pleural mesothelioma or another asbestos-related disease, the doctor will schedule additional tests.

Dr. Farid Gharagozloo describes the diagnostic process for pleural mesothelioma.

Imaging Scans for Pleural Mesothelioma

Imaging scans and other tests are imperative to making an accurate diagnosis of pleural mesothelioma. When a patient presents with shortness of breath or a constant cough, the first test most doctors perform is a chest X-ray.

While a chest X-ray may indicate an asbestos-related disease, the results are less detailed than those of more advanced imaging tests. However, chest X-rays will sometimes capture several signs of pleural mesothelioma, including pleural effusion, thickening of the pleural lung lining and calcium deposits on the lining.

The imaging scan of choice for the initial diagnosis of pleural mesothelioma is a computed tomography (CT) scan, also known as a CAT scan. Instead of taking one picture of the patient’s body like an X-ray, a CT scan takes many detailed cross-sectional images. A computer then combines these images, allowing doctors to look at the patient’s chest in slices.

Although CT scans take longer than traditional X-rays, they produce images that more clearly display the size and location of mesothelioma tumors and the extent to which they have spread throughout the body. A CT scan will commonly find pleural thickening, one sign that suggests pleural mesothelioma.

An even higher level of detail can be attained with a magnetic resonance imaging (MRI) scan, which produces an image with magnets and radio waves. This scan is generally better for detecting pleural mesothelioma that has spread into vital structures of the chest, such as the diaphragm (breathing muscle) or mediastinum (a group of structures located behind the breast bone and between the lungs). This type of scan is valuable because it can help identify the patients who will benefit most from surgery.

In some cases, doctors may confuse scar tissue for cancer on imaging scans. Positron emission tomography (PET) scans allow doctors to clearly distinguish between the two. This imaging technique uses a radioactive form of sugar that cancer cells absorb in large amounts. Although not very detailed, a PET scan can clearly display where mesothelioma cancer has spread.

A relatively new technique called the PET-CT scan, which combines PET and CT scan technologies into one machine, overcomes the limitations of the PET scan. Because studies demonstrate the PET-CT scan can gauge a patient’s response to chemotherapy better than either scan alone, it is a highly useful tool in pleural mesothelioma treatment.

Imaging scans are essential to determining a cancer’s stage. Staging assesses the growth and spread of a person’s cancer. Imaging scans are the primary diagnostic tool that allows doctors to evaluate the growth and spread of pleural mesothelioma.

An MRI scan can show whether the cancer has spread locally throughout the chest, which helps distinguish between stages I through III. A PET-CT scan is especially helpful at showing spread to distant organs, which can help determine if the cancer is in stage IV yet. To this end, imaging scans are crucial to reaching a prognosis because staging is the biggest determinant of prognosis.

Biopsy Procedures

If imaging scans reveal any suspicious growths on the pleura or other structures of the chest, doctors must collect a tissue sample for further testing, and sometimes pleural fluid is collected and tested. The procedure to remove these samples is known as a biopsy, and there are several biopsy techniques doctors can use to make a diagnosis. Biopsy is the most effective procedure for diagnosing pleural mesothelioma.

Samples can be collected using a needle or with other devices through open surgery. Regardless of approach, biopsy samples are sent to a medical specialist called a pathologist, who looks at samples through a microscope and performs other laboratory tests to determine if the patient has cancer, and if so, what type.

In one biopsy technique called thoracentesis, doctors use a needle to collect a fluid sample from the pleural cavity of patients with pleural effusion. The sensitivity of this technique is less than 50 percent for pleural mesothelioma, meaning it accurately identifies patients with the disease less than half the time.

A more effective technique called needle biopsy uses a long, hollow needle to extract a small tumor sample. In some cases, however, the tumor sample is not large enough and other techniques may be required. If a larger sample is needed, the doctor may perform an open surgical biopsy and remove some of the tumor through an incision in the chest.

The most accurate and highly-recommended biopsy technique for diagnosing pleural mesothelioma is called video-assisted thoracic surgery (VATS) or a thoracoscopy. In this procedure, doctors put patients under general anesthesia before making one or two small incisions in the chest. Using a camera-fitted tool called a thoracoscope, the surgeon watches a video screen as he or she collects a sample of tumor cells. VATS can correctly identify patients with pleural mesothelioma with a sensitivity of 95 to 98 percent, and the procedure usually takes less than an hour. The recovery time with VATS is also significantly less than open surgical biopsy.

It’s important to work with a mesothelioma specialist and a cancer center that has vast experience with pleural mesothelioma during the diagnostic process. The pathologists who work for these cancer centers have more experience correctly identifying pleural mesothelioma with biopsy samples. When an experienced pathologist is overseeing biopsy testing, the chance of a misdiagnosis is low.

A second opinion with a specialist is highly recommended to patients who received a mesothelioma diagnosis from a cancer center or oncologist who doesn’t have extensive experience with mesothelioma. Pleural mesothelioma can be confused with adenocarcinoma, a form of lung cancer. Experienced pathologists know how to tell the difference.

Sometimes, a second opinion can result in a more accurate staging diagnosis. Doctors and cancer centers experienced in mesothelioma can better discern imaging scans and other tests that can pinpoint a pleural mesothelioma diagnosis.

Blood Tests for Pleural Mesothelioma

Although biopsy is the benchmark approach for accurately diagnosing pleural mesothelioma, researchers have developed numerous tests that can assist with diagnosis by identifying certain substances, called biomarkers, in the patient’s blood.

In 2007, the U.S. Food and Drug Administration (FDA) approved the MESOMARK assay, a test that measures the levels of biomarkers called soluble mesothelin-related peptides (SMRPs) in the blood. Researchers have determined that SMRP concentrations are higher in pleural mesothelioma patients than healthy people, making the MESOMARK test useful for identifying patients with mesothelioma and measuring their response to therapy.

Since the development of the MESOMARK assay, researchers have been actively seeking new and more effective biomarkers for pleural mesothelioma. In an October 2012 article published in the New England Journal of Medicine, researchers reported on fibulin-3, a protein found in the blood and pleural fluid that can be used to distinguish mesothelioma-related pleural effusions from pleural effusions from other causes.

Researchers have also investigated several gene-encoding molecules called microRNA as potential mesothelioma biomarkers. One such molecule, miR-625-3p, is four times as prevalent in pleural mesothelioma patients as in those without the disease. Although this biomarker is not highly accurate, several studies demonstrate the test performs just as well as other biomarker tests.

Blood tests show great promise for accelerating the detection of mesothelioma, which in turn could lead to earlier treatment and improved survival. However, none of these tests currently offers a high enough level of accuracy to screen for mesothelioma or diagnose it independently. Until researchers discover more accurate mesothelioma biomarkers, blood tests will primarily be used to monitor the progress of patients during and after treatment.

What to Do After Diagnosis

Step 1:

Find a pleural mesothelioma specialist

Unless you were diagnosed by an experienced mesothelioma specialist, the first step to take after diagnosis is finding an expert to oversee your treatment. Working with a pleural mesothelioma specialist will ensure you receive the best possible care.

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Step 2:

Know your treatment options

Learn all that you can about pleural mesothelioma treatment options. Knowing your options will help you understand why certain therapies are recommended and will help mentally prepare you for the road ahead. Your treatment options will depend greatly on the cancer’s stage, your age and overall health.

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Step 3:

Get the support you need

Establishing your support system will provide comfort and relief during the times when you’ll need it most. Reach out to family and friends, as well as neighbors and members of your community, such as a local church or nonprofit.

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Ask your oncologist if your treatment center offers mental health counseling for cancer patients and their families, and consider joining a cancer support group. Many people with mesothelioma qualify for financial support and veterans with mesothelioma can get help filing VA claims.

Resources like these are available to help people with pleural mesothelioma throughout their journey.

Dr. Snehal Smart

Snehal Smart

Snehal Smart is the Pleural Mesothelioma Center’s in-house medical doctor, serving as both an experienced Patient Advocate and an expert medical writer for the website. When she is not providing one-on-one assistance to patients, Dr. Snehal stays current on the latest medical research, reading peer-reviewed studies and interviewing oncologists to learn about advancements in diagnostic tools and cancer treatments.

Last Modified October 10, 2018

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