Your doctor will ask about your symptoms and other medical conditions you have had. He or she will then examine you.
Because mesothelioma symptoms can be caused by other medical conditions, your doctor will probably run a few tests. These tests include an electrocardiogram (ECG), to check your heart, and a chest or abdominal x-ray.
If these tests show abnormalities in the lungs or pleura, you will need a computed tomography (CT) scan or a magnetic resonance imaging (MRI) scan. These imaging studies help your doctor determine the size and location of any tumors in the chest or abdomen.
If you have fluid in your chest or abdomen, your doctor may use a needle or thin tube to remove a small sample of it for examination. (Fluid may also be drained to relieve chest pain and shortness of breath.) Occasionally, mesothelioma can be diagnosed from this fluid sample alone. But in most cases, your doctor will take a tissue sample (biopsy), too.
Depending on the tumor's location, your doctor will make a small cut through the chest wall or into the abdomen. He or she will then insert a lighted tube through the incision to see the tumor and remove a tiny piece of it. Your doctor may also look for masses in your airways or remove lymph nodes.
Investigational blood tests that check levels of two chemicals—osteopontin and mesothelin—may help diagnose mesothelioma. (They may also assess a patient's response to treatment.) Tests for these biomarkers are available as part of some clinical trials.
If your doctor diagnoses pleural mesothelioma, the next step is to determine the cancer's stage. This is a measure of how far the tumor has spread. These are the stages of pleural mesothelioma:
Stage I. The tumor is only in the lining on one side of the chest or diaphragm. There may be small spots on cancer on the lining of the lung. There are no signs that the cancer has spread to more distant sites.
Stage II. The cancer involves one side of the chest or diaphragm, and it has grown into a large part of the lining of the lung, the diaphragm, or the lung itself. It has not spread to the lymph nodes or to distant sites.
Stage III. The cancer affects one side of the chest, and it has grown into the chest wall or the outer covering of the heart. It may have spread to lymph nodes on the same side as the tumor, but not to other lymph nodes. It has not spread to distant sites.
Stage IV. The cancer affects one or both sides of the chest. It has spread deep into the chest wall, through the diaphragm, into the spine, through the lining of the heart, or into the heart itself. It may have spread to lymph nodes and to distant sites.
Stage I also is called localized disease. Stages II, III, and IV are called advanced disease. If the disease returns after treatment, it is called recurrent mesothelioma.
Doctors don't have a staging system for mesothelioma in the abdomen.