Introduction: Who Should Seek Diagnostic Testing

If you have ever worked with asbestos or lived in a place where asbestos was present, and you begin experiencing certain symptoms, it is important to see a doctor. People who notice ongoing chest pain, shortness of breath, or a persistent cough that does not go away should seek medical advice, especially if they have a history of asbestos exposure. Because pleural mesothelioma can take anywhere from 20 to 50 years to develop after someone first breathes in asbestos fibers, symptoms may not appear until decades later.^[1][12]

Many patients delay visiting their healthcare provider because the early signs can seem mild or similar to other, less serious conditions. However, early detection of pleural mesothelioma can make a significant difference in how the disease is managed. If you or a loved one has a known history of asbestos exposure—whether from working in construction, shipyards, or military service, or from living with someone who worked with asbestos—it is advisable to share this information with your doctor. This background will help them understand the risks and consider mesothelioma as a possible cause of your symptoms.^[4]

Even people without obvious symptoms may benefit from regular checkups if they have been exposed to asbestos. Doctors may recommend monitoring for signs of asbestos-related diseases, which can include not only mesothelioma but also other lung conditions. If you experience unexplained weight loss, fatigue, fever, or night sweats along with breathing difficulties, these could be warning signs that warrant further investigation.^[1]

Classic Diagnostic Methods for Identifying Pleural Mesothelioma

Diagnosing pleural mesothelioma is not always straightforward. The process usually begins with a physical examination, during which a healthcare professional will check for lumps under the skin of the chest, listen to your breathing, and ask about your symptoms and medical history. The doctor will be especially interested in learning about any past exposure to asbestos, as this is the primary cause of pleural mesothelioma in about 70% or more of cases.^[1]

Imaging Tests

Once the doctor suspects a problem, imaging tests are typically the next step. A chest X-ray is often the first test performed. It can reveal fluid buildup around the lungs, which is a common sign of pleural mesothelioma. However, because a chest X-ray does not always provide enough detail, more advanced imaging is usually needed.^[5][16]

A computed tomography scan, or CT scan, uses X-rays and a computer to create detailed, three-dimensional images of the chest. This scan helps doctors see the extent of the disease, whether the cancer has spread beyond the lining of the lungs, and how much of the pleura is affected. CT scans of the chest and abdomen are often used together to check if the cancer has spread to other parts of the body.^[6][16]

Magnetic resonance imaging, or MRI, is another imaging technique that uses magnets and radio waves instead of radiation to produce images. MRI can be helpful in evaluating the soft tissues around the lungs and in planning surgery. Some patients may also undergo a positron emission tomography scan, known as a PET scan, which uses a small amount of radioactive material to highlight areas where cancer cells are active. This test can help identify whether the cancer has spread to lymph nodes or other organs.^[16]

Fluid and Tissue Sampling

Imaging tests can suggest the presence of mesothelioma, but they cannot confirm the diagnosis on their own. To be certain, doctors need to examine cells or tissue under a microscope. This is where biopsy procedures come in. A biopsy involves removing a small sample of tissue or fluid from the affected area so that it can be tested in a laboratory.^[16]

One common method is thoracentesis, also called pleural fluid sampling. In this procedure, a doctor inserts a thin needle through the skin and into the space between the lungs and chest wall to remove some of the fluid that has built up. This fluid is then examined for cancer cells. While thoracentesis can provide important clues, it does not always give a definitive answer because mesothelioma cells can be hard to identify in fluid alone.^[7]

If the fluid test is not conclusive, a more invasive biopsy may be needed. A needle biopsy involves inserting a needle through the skin to remove a small piece of tissue from the pleura. This tissue sample is sent to a lab where specialists examine it under a microscope to look for cancer cells and determine the type of mesothelioma.^[16]

In some cases, doctors perform a surgical biopsy. One type is called a thoracoscopy, where a surgeon makes a small cut in the chest and inserts a thin tube with a camera on the end. This allows the surgeon to see inside the chest cavity and take samples of tissue from the pleura. Another option is a mediastinoscopy, which is used to examine and biopsy lymph nodes in the area between the lungs. These procedures are more involved but provide the most accurate diagnosis.^[16]

Understanding the Type of Mesothelioma

Once a biopsy has been taken, pathologists examine the tissue to identify the type of cells involved. Pleural mesothelioma is classified into three main types based on cell appearance: epithelioid, sarcomatoid, and biphasic. Epithelioid mesothelioma is the most common form and tends to respond better to treatment. Sarcomatoid mesothelioma is rarer and more aggressive, meaning it grows and spreads more quickly. Biphasic mesothelioma contains a mix of both cell types, and the prognosis depends on the ratio of epithelioid to sarcomatoid cells.^[1][9]

Knowing the cell type is important because it helps doctors predict how the cancer might behave and what treatments are most likely to be effective. It also plays a role in determining the patient’s overall outlook.

Staging the Disease

After confirming the diagnosis, doctors need to determine the stage of the cancer, which describes how far it has spread. Staging helps guide treatment decisions. The stages of pleural mesothelioma range from 1 to 4, with stage 1 being the least advanced and stage 4 being the most advanced. To determine the stage, doctors may use additional imaging tests, such as CT scans, MRI, or PET scans, to check whether the cancer has spread to lymph nodes or other parts of the body.^[16][18]

Early-stage mesothelioma that is confined to the pleura is easier to treat with surgery and other therapies. Advanced-stage disease, where the cancer has spread to other organs, is more difficult to manage, and treatment focuses more on controlling symptoms and extending life.^[6]

Diagnostic Tests for Clinical Trial Qualification

Clinical trials are research studies that test new treatments or combinations of treatments to find better ways to manage pleural mesothelioma. If you are considering joining a clinical trial, you will need to undergo specific tests to see if you meet the requirements for participation. These tests help researchers make sure that the treatment being studied is appropriate for your condition and that it is safe for you to participate.^[6]

General Health and Organ Function Tests

Before enrolling in a clinical trial, doctors will assess your overall health and the function of your major organs. Blood tests are commonly used to check your liver and kidney function, as well as your blood cell counts. These tests help determine whether your body can tolerate the experimental treatment, especially if it involves chemotherapy or other drugs that can affect organ function.^[18]

Your doctor will also evaluate your performance status, which is a measure of how well you are able to carry out daily activities. Performance status is often rated using scales such as the Eastern Cooperative Oncology Group (ECOG) scale. Patients with a better performance status are more likely to be eligible for clinical trials and to tolerate aggressive treatments.^[18]

Imaging and Staging Evaluations

Clinical trials often require up-to-date imaging studies to confirm the extent and location of the cancer. This may include CT scans, MRI, or PET scans. These images help researchers determine the stage of your mesothelioma and whether it has spread to other parts of your body. Accurate staging is essential because many trials are designed for patients at specific stages of the disease.^[18]

Confirmation of Diagnosis

To join a clinical trial, you must have a confirmed diagnosis of pleural mesothelioma, which usually means that a biopsy has been performed and examined by a pathologist. Some trials may also require that the biopsy tissue be reviewed by a central laboratory to ensure the diagnosis is accurate. In addition, certain trials may look for specific genetic markers or changes in the tumor cells that predict how the cancer will respond to the treatment being tested.^[18]

Screening for Genetic and Molecular Features

Some clinical trials focus on treatments that target specific genetic mutations or proteins in cancer cells. For example, researchers have found that certain genetic changes, such as mutations in the BRCA1-associated protein 1 (BAP1) gene, are linked to mesothelioma. If your tumor has certain molecular features, you may be eligible for trials testing targeted therapies or immunotherapies designed to work against those specific changes.^[3]

To find out if your tumor has these features, your doctor may order additional tests on your biopsy sample. These tests look at the genes and proteins inside the cancer cells and can help guide decisions about which treatments or clinical trials might be most effective for you.

Prognostic Scoring Systems

Researchers use prognostic scoring systems to predict how well a patient might respond to treatment and to help organize patients into groups for clinical trials. Two commonly used systems are the Cancer and Leukemia Group B (CALGB) index and the European Organisation for the Research and Treatment of Cancer (EORTC) index. These systems take into account factors such as your age, performance status, white blood cell count, hemoglobin levels, and the type of mesothelioma cells you have.^[18]

By grouping patients based on these factors, researchers can better understand which treatments work best for different groups of people. If you are considering a clinical trial, your doctor may use one of these scoring systems to help determine your eligibility and to give you an idea of what outcomes you might expect.