Mesothelioma is cancer of the mesothelium, a membrane that lines the inside of the body's cavities, such as the chest or abdomen. Most often, mesothelioma happens in the inner lining of the chest, called the pleura.
Mesothelioma is most often diagnosed after a patient sees a doctor because of symptoms such as pain in the lower back, shortness of breath, fatigue, weight loss, abdominal pain, or swelling. But symptoms alone will not tell your doctor if you have mesothelioma. A medical history, physical exam, and diagnostic tests are necessary to confirm a mesothelioma diagnosis.
Medical History and Physical Exam
Because mesothelioma is uncommon, it is often misdiagnosed at first. If you have symptoms that suggest you might have mesothelioma, your doctor will likely take a complete medical history to check for symptoms and possible things that raise your risk of having the disease, especially asbestos exposure. Exposure to asbestos is the No. 1 thing that makes mesothelioma more likely.
Your doctor will also ask about your general health and do an exam to check for possible signs of mesothelioma. These may include fluid in the chest cavity, abdomen, or pericardium (the thin membrane around the heart).
Depending on the findings of the exam, your doctor may refer you for mesothelioma testing.
There are several different types of mesothelioma tests. These include:
Blood tests. Blood levels of 3 substances -- fibulin-3, osteopontin, and soluble mesothelin-related peptides (SMRPs) -- are often higher in people with mesothelioma. Although these blood tests cannot confirm a diagnosis of mesothelioma -- more study is needed before they can be of reliable use in a clinical setting -- high levels of these substances make the disease more likely.
Fluid and tissue sample tests. If you have a buildup of fluid in the body that may be related to mesothelioma, your doctor can remove a sample of the fluid by putting a needle through the skin into the area of fluid buildup. The fluid can then be examined under a microscope for cancer cells. If cancer cells are found, further tests can tell if the cancer is mesothelioma.
This test goes by different names, depending on where the fluid is:
- Thoracentesis -- chest cavity
- Paracentesis -- abdomen
- Pericardiocentesis -- membrane around the heart
Even if your doctor does not find mesothelioma cells in fluid, that doesn't necessarily mean you don't have mesothelioma. Sometimes samples of actual tissue (biopsies) are needed to diagnose mesothelioma.
Biopsies. There are ways to remove tissue to be examined for mesothelioma. They include:
- Needle biopsy. This involves inserting a long, hollow needle through the skin to remove a tiny piece of a tumor. Your doctor may use imaging tests to guide the needle into the tumor. In some cases, the sample may be too small to make a diagnosis and a more invasive procedure is needed.
Thoracoscopy, laparoscopy, and mediastinoscopy. In these procedures, the doctor inserts a thin, lighted scope through a small cut in the skin to see potential areas of mesothelioma. Small tools, put in through other cuts, can be used to remove pieces of tissue to examine under a microscope. The specific procedure depends on the area being examined:
- Thoracoscopy examines the space between the lungs and chest wall.
- Laparoscopy examines the inside of the abdomen.
- Mediastinoscopy examines the center of the chest, around the heart.
- Surgical biopsy. In some cases, more invasive procedures may be needed to get a large enough tissue sample to make a diagnosis. In that case, a surgeon may perform a thoracotomy (opening the chest cavity) or laparotomy (opening the abdominal cavity) to remove a larger sample of tumor or the whole tumor.
- Endobronchial ultrasound-guided biopsy. This procedure involves passing a long, thin, flexible tube down the throat to examine the lungs for tumors. The tube also has an ultrasound, so the doctor can better identify the tumor and the proper place to biopsy. If a tumor is found, the doctor can remove a small sample of it through the tube.
Imaging tests. These tests allow your doctor to view the inside of your body without making cuts. Imaging tests commonly used in mesothelioma diagnosis include:
- Chest X-ray. An X-ray of the chest may show abnormal thickening of or calcium deposits on the lung lining, fluid in the space between the lungs and chest wall, or changes in the lungs, which could suggest mesothelioma.
- Computed tomography (CT). The CT scan is a procedure that uses multiple X-rays and a computer to create detailed images of the inside of the body. CT scans are often used to look for signs of cancer, help find where the cancer is, and to check if the cancer has spread.
- Positron emission tomography (PET). This test involves giving a shot of a compound containing a radioactive atom and then taking pictures of the body. Cancer cells absorb large amounts of the radioactive compound and show up brighter than normal tissue on the images. Doctors then focus further tests on these areas of potential cancer.
- Magnetic resonance imaging (MRI). MRI scans use radio waves and strong magnets to make detailed images of the body. Because they provide detailed images of soft tissues, they may help your doctor find where the tumor is. For mesotheliomas that involve the diaphragm (a dome-shaped muscle under the lungs), MRI scans may be particularly useful.
Certain things affect a mesothelioma prognosis as well as your options for mesothelioma treatment. They include the following:
- The stage of the cancer, or the extent of cancer in the body. The stage is usually based on the size of the tumor, whether there are cancer cells in the lymph nodes, and whether cancer has spread beyond its original site.
- The size of the mesothelioma
- Whether the mesothelioma can be removed completely by surgery
- The amount of fluid in the chest or abdomen
- Your age and general health
- The type of mesothelioma cells
- Whether the cancer has just been diagnosed or has already been treated and come back
Treatment for mesothelioma depends on a number of things, including those mentioned above. Three standard types of treatment are used: surgery, radiation, and chemotherapy. Treating mesothelioma often involves a combination of two or all three.
Surgery. The main surgeries used in mesothelioma treatment are:
- Wide local excision, which removes the cancer along with some of the healthy surrounding tissue
- Pleurectomy and decortication, in which the surgeon removes part of the covering of the lungs, chest lining, and outside surface of the lungs
- Extrapleural pneumonectomy, which involves removing one whole lung and part of the lining of the chest, the diaphragm, and the lining of the sac around the heart
- Pleurodesis, which involves using a chemical or drug to make the lung lining scar and stick to the lung. The scarring stops the buildup of fluid. This is used for symptom control and isn’t meant to be a cure.
Radiation therapy. This type of cancer treatment uses high-energy X-rays and other types of radiation to kill mesothelioma cells or keep them from growing. Radiation may be given externally or internally. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into the area near the mesothelioma.
Chemotherapy. This uses drugs to stop the growth of cancerous mesothelioma cells, either by killing the cells or by stopping them from dividing. Chemotherapy can be given by mouth, injected into a vein or muscle to enter the bloodstream and reach mesothelioma cells throughout the body, or it can be placed directly into the affected area of the body to mainly affect mesothelioma cells in that area. Sometimes, doctors use more than one chemotherapy drug. This is called combination chemotherapy.