How is malignant mesothelioma found?
Screening for mesothelioma is not recommended in people who are not at increased risk. It is not clear how useful chest x-rays or CT scans are in finding mesothelioma early, but some doctors may advise them for people who have been exposed to asbestos.
Blood tests to look for mesothelioma are now being studied. These tests measure the blood levels of certain substances that are higher in people who have mesothelioma. But right now blood tests are used mainly to follow the course of the disease in people who are already known to have mesothelioma.
Symptoms of mesothelioma
Most of the time mesothelioma is found when a person goes to a doctor because of symptoms. Early symptoms are not specific to the disease, so at first people may ignore them or mistake them for common, minor problems. Most people with this type of cancer have symptoms for at least a few months before the cancer is found.
Symptoms of pleural mesothelioma (lining of the chest) can include:
- Pain in the lower back or at the side of the chest
- Shortness of breath
- Weight loss
- Trouble swallowing
- Swelling of the face and arms
Symptoms of peritoneal mesothelioma (lining of the abdominal cavity) can include:
- Belly pain
- Fluid or swelling in the abdomen (belly)
- Weight loss
- Nausea and vomiting
Of course, these same symptoms can also be caused by other problems. But if you have worked with asbestos and you have any of these symptoms, you should see a doctor right away.
Medical history and physical exam
If you have any signs or symptoms that suggest you might have mesothelioma, your doctor will want to take a complete medical history to learn about your symptoms and possible risk factors, especially about asbestos exposure. You will also be asked about your general health, and the doctor will do a physical exam. The exam can help tell if you have fluid in the chest, belly, or around the heart. This fluid can be a sign of mesothelioma.
If symptoms or the results of the exam suggest you might have mesothelioma, tests will be needed to make sure. These might include imaging tests, blood tests, and other tests.
These tests allow the doctor to see pictures of the inside of your body. They might be done for a number of reasons, such as to help find an area that might be cancer, to learn how far cancer has spread, and to see if treatment is working.
Chest x-ray: This is often the first test done if someone has symptoms such as a constant cough or shortness of breath. An x-ray might show thickening of the lining of the lungs or other changes caused by asbestos. These changes may suggest mesothelioma.
CT scan: A CT scan (or CAT scan) is like an x-ray but it gives detailed cross-sectional pictures of your body. Instead of taking one picture, a CT scanner takes many pictures as it moves around you. A computer then combines these pictures to show slices of your body.
CT scans are often used to help decide if you have mesothelioma and to help find the exact place of the cancer. They can also help show how much the cancer has spread.
Before any pictures are taken, you may be asked to drink a liquid that helps outline your intestines (gut). You may also get an IV (intravenous) line which is used to put a different kind of contrast dye into your blood. This helps better outlines parts of in your body. Some people are allergic to the dye and get hives, a flushed feeling, or – rarely – more serious problems like trouble breathing and low blood pressure. Be sure to tell your doctor if you have any allergies or have ever had a problem from any dye used for x-rays.
CT scans take longer than regular x-rays, and you need to lie still on a table while they are being done. During the test, the table slides in and out of the scanner, a ring-shaped machine that goes around the table. Some types of CT scans use a faster machine.
PET scan: A PET scan uses glucose (a form of sugar) that contains a radioactive substance. Cancer cells in the body take in large amounts of the radioactive sugar and a special camera can show these radioactive spots.
This test can help tell whether a thickening of the tissues is cancer or just scar tissue. It can also show the spread of cancer. A PET scan can also be useful if your doctor thinks the cancer may have spread but doesn’t know where. The picture from a PET scan is not detailed, but shows the whole body at once. Some newer machines are able to do both a PET and CT scan at the same time.
MRI scan: This test uses radio waves and strong magnets instead of x-rays to take pictures. It gives a very detailed picture of your insides. MRI scans may be useful in looking at the thin band of breathing muscle below the lungs (the diaphragm). Mesothelioma can spread there.
A contrast dye might be used just as with CT scans. MRI scans take longer than CT scans – often up to an hour. Also, you may have to lie inside a narrow tube, which is confining and can upset people with a fear of enclosed spaces. Special, more open MRI machines may be an option in some cases. The machine makes a thumping noise; some places will give you earplugs to help block out the sound.
Blood levels of certain substances are often high in people with mesothelioma. They may help show if a person likely has mesothelioma. But so far, these blood tests have proven more useful in people who already have mesothelioma to follow their progress during and after treatment.
If you are found to have mesothelioma, other blood tests will be done to check blood cell counts and levels of certain chemicals in the blood. These tests can give the doctor an idea of how much the disease has spread and how well organs like the liver and kidneys are working.
Tests of fluid and tissue samples
To make a diagnosis of mesothelioma, the doctor removes cells from an abnormal area and sends them to be looked at under a microscope.
Removing fluid for testing
If you have a buildup of fluid in the body that may be caused by mesothelioma, a sample of this fluid can be taken. The skin is numbed and a thin, hollow needle is put through the skin into the fluid, which is drawn out and sent to the lab. The fluid is tested to see if there are cancer cells in it.
This test has different names depending on where the fluid is:
- Thoracentesis removes fluid from the chest.
- Paracentesis removes fluid from the abdomen (belly).
- Pericardiocentesis removes fluid from the sac around the heart.
Finding cancer cells tells the doctor that cancer is present, but not finding any cancer cells in the fluid does not always mean there is no cancer. In many cases, doctors need to get a sample of the tissue (called a biopsy) to find out if you have mesothelioma.
For a biopsy, a small amount of tissue is taken out and looked at under a microscope to see whether it contains cancer.
Needle biopsy: Tumors in the chest are sometimes sampled by needle biopsy. A long, hollow needle is passed through the skin in the chest, between the ribs, and into the tumor. A small sample can be removed to be looked at under the microscope. This is often done using just numbing medicine. Sometimes the sample is not large enough to tell for sure whether there is cancer. If this happens, another kind of biopsy may be needed.
Endoscopic biopsies: An endoscope (scope) is a thin, tube-like tool used to look inside the body. It has a light and a lens (or video camera) on the end and tools that can be used to remove tissue that looks like it may be cancer. There are a number of different types of scopes. They are named after the part of the body that they are used to look at. For instance:
- A thoracoscope is used to look inside the chest. It is inserted through a small cut in the chest wall.
- A mediastinoscope is used to look at the space between the lungs. It is inserted through a small cut in the front of the neck.
- A bronchoscope is used to look at the lining of the main airways in the lungs. It is passed down the throat, so it does not require any cuts. In some cases, the scope may be fitted with a small ultrasound device on the end to help the doctor see lymph nodes in the chest and take samples of them, if needed.
- A laparoscope is used to look inside the belly. It is inserted through small cuts in the front of the belly.
- will be asleep (under general anesthesia) or deeply sedated for any type of endoscopic biopsy.
Open surgical biopsy: In some cases, surgery may be needed to get a large enough tissue sample. By making a cut (incision) in either the chest or the belly, the doctor can remove a larger sample of tumor or, sometimes, the whole tumor.
Testing the samples in the lab
No matter which approach is used to get them, biopsy and fluid samples are sent to the pathology lab. There, a doctor will look at them under a microscope and do other tests to decide whether cancer is present (and if so, what type of cancer it is).
It is often hard to tell whether it is mesothelioma by just looking at the cells from fluid samples (or even tissue samples). So special lab tests that look at things like proteins may be done, too.
Pulmonary function tests
Pulmonary function tests (PFTs) may be done after mesothelioma is found to see how well your lungs are working. This is important if you might need surgery to take out part or all of a lung. The doctors need to know how well your lungs are working before the surgery. These tests can give the doctor an idea of how much lung can safely be removed. For PFTs, you breathe in and out through a tube that is hooked up to a machine that measures your lung function.
Last Medical Review: 10/02/2012
Last Revised: 10/02/2012