Mesothelioma is a rare type of cancer that that develops in the pleura, a thin membrane that separates the lung from the chest wall. It usually occurs from prior exposure to asbestos, a type of mineral fiber used in the insulation industry.
In general, cancer begins when a series of genetic mutations occur within a cell, causing the cell to grow and multiply out of control. It isn’t clear what causes the initial genetic mutations that lead to mesothelioma, though researchers have identified factors that may increase the risk. It’s likely that cancers form because of an interaction between many factors, such as inherited conditions, your environment, your health conditions and your lifestyle choices.
Malignancies involving mesothelial cells that normally line the body cavities, including the pleura (see the image below), peritoneum, pericardium, and testis, are known as malignant mesothelioma. Asbestos, particularly the types of amphibole asbestos known as crocidolite and amosite asbestos, is the principal carcinogen implicated in the pathogenesis of malignant pleural mesothelioma.
Signs and symptoms of mesothelioma vary depending on where the cancer occurs.
Pleural mesothelioma, which affects the tissue that surrounds the lungs, causes signs and symptoms that may include:
- Chest pain under the rib cage
- Painful coughing
- Shortness of breath
- Unusual lumps of tissue under the skin on your chest
- Unexplained weight loss
Peritoneal mesothelioma, which occurs in tissue in the abdomen, causes signs and symptoms that may include:
- Abdominal pain
- Abdominal swelling
- Lumps of tissue in the abdomen
- Unexplained weight loss
OTHER FORMS OF MESOTHELIOMA
Signs and symptoms of other types of mesothelioma are unclear, since these forms of the disease are very rare.
Pericardial mesothelioma, which affects tissue that surrounds the heart, can cause signs and symptoms such as breathing difficulty and chest pains.
Mesothelioma of tunica vaginalis, which affects tissue surrounding the testicles, may be first detected as swelling or a mass on a testicle.
If you have signs and symptoms that might indicate mesothelioma, your doctor will conduct a physical exam to check for any lumps or other unusual signs.
Your doctor may order imaging scans, such as a chest X-ray and a computerized tomography (CT) scan of your chest or abdomen, to look for abnormalities.
Based on the findings, you may undergo further testing to determine whether mesothelioma or another disease is causing your signs and symptoms.
Biopsy, a procedure to remove a small portion of tissue for laboratory examination, is the only way to determine whether you have mesothelioma. Depending on what area of your body is affected, your doctor selects the right biopsy procedure for you.
- Fine-needle aspiration. The doctor removes fluid or a piece of tissue with a small needle inserted into your chest or abdomen.
- Thoracoscopy. Thoracoscopy allows the surgeon to see inside your chest. In this procedure, the surgeon makes one or more small incisions between your ribs. A tube with a tiny video camera is then inserted into your chest cavity — a procedure sometimes called video-assisted thoracoscopic surgery (VATS). Special surgical tools allow your surgeon to cut away small pieces of tissue for testing.
- Laparoscopy. Laparoscopy allows the surgeon to see inside your abdomen. Using one or more small incisions into your abdomen, the surgeon inserts a tiny camera and special surgical tools to obtain a small piece of tissue for examination.
- Thoracotomy. Thoracotomy is surgery to open your chest between the ribs to allow a surgeon to check for signs of disease. A sample of tissue may be removed for testing.
- Laparotomy. Laparotomy is surgery to open your abdomen to allow a surgeon to check for signs of disease. A sample of tissue may be removed for testing.
The tissue sample is analyzed under a microscope to see whether the abnormal tissue is mesothelioma and what types of cells are involved. The type of mesothelioma you have determines your treatment plan.
Once mesothelioma is diagnosed, your doctor orders other tests to determine the extent, or stage, of the cancer. Imaging tests that may help determine the stage of your cancer may include:
- CT scans of the chest and abdomen
- Magnetic resonance imaging (MRI)
- Positron emission tomography (PET)
Your doctor determines which tests are more appropriate for you. Not every person needs every test.
Once the extent of pleural mesothelioma is determined, a stage is assigned.
- Stage I mesothelioma is considered localized cancer, meaning it’s limited to one portion of the lining of the chest.
- Stage II mesothelioma may have spread beyond the lining of the chest to the diaphragm or to a lung.
- Stage III mesothelioma may have spread to other structures within the chest and may involve nearby lymph nodes.
- Stage IV mesothelioma is an advanced cancer that has spread more extensively within the chest. Stage IV may also indicate that mesothelioma has spread to distant areas of the body, such as the brain, liver and lymph nodes elsewhere in the chest.
Formal stages aren’t available for other types of mesothelioma because these types are rare and aren’t well-studied.
Doctors offer three primary types of treatment to mesothelioma patients: Surgery, chemotherapy and radiation. The types of treatment you receive depend on your diagnosis, the stage and type of your mesothelioma and your overall health.
If the cancer has not yet spread, a combination of radiation, surgery and chemotherapy likely will be offered to you. This combined approach to treatment is called multimodal therapy.
If the mesothelioma already has spread significantly, doctors typically recommend palliative treatments that can help alleviate pain, breathing problems and other cancer symptoms that lessen your quality of life. You are still likely to be offered radiation and chemotherapy, but probably not major surgery options.
Radiation therapy can soothe pain and correct breathing issues by shrinking tumors that press on your nerves, veins and airways. Chemotherapy also shrinks tumors, helping with chest pain and night sweats. Non-curative surgeries can remove tumors that cause troublesome symptoms, or drain fluid that builds up in the chest or abdomen.
You may also want to talk to your doctor about other treatment options beyond surgery, chemotherapy and radiation therapy. Experimental treatments exist, mostly in clinical trials, and sometimes they can make a huge difference.
Some patients also pursue alternative treatments like massage therapy, acupuncture or yoga. These can often be added to standard treatments like chemotherapy, so talk with your doctor about which therapies you’d like to explore.