About malignant mesothelioma
What is malignant mesothelioma?
Mesothelioma is a rare form of cancer that affects the membrane that covers and protects various internal organs of the body (mesothelium). The mesothelium is composed of two layers of specialized cells known as mesothelial cells. One layer directly surrounds an organ; the other forms a protective sac around the organ. The most common form of mesothelioma affects the membrane or sac that lines the lungs (pleura). Other common sites include the membrane lining the stomach (peritoneum) and the membrane lining the heart (pericardium).
The term "cancer" refers to a group of diseases characterized by abnormal, uncontrolled cellular growth (e.g., mesothelial cells) that invades surrounding tissues and may spread (metastasize) to distant bodily tissues or organs via the bloodstream, the lymphatic system, or other means. Different forms of cancer, including mesothelioma, may be classified based upon the cell type involved, the specific nature of the malignancy, the tissues or organs affected, and the disease's clinical course. Symptoms of mesothelioma vary depending upon the location, type and stage of the cancer. Approximately 70 to 80 percent of cases of mesothelioma result from exposure to asbestos. Symptoms of mesothelioma may not appear until up to 50 years after initial exposure to asbestos. However, after symptoms began apparent, mesothelioma may rapidly progress to cause life-threatening complications.
What are the symptoms for malignant mesothelioma?
Pleural mesothelioma, which affects the tissue that surrounds the lungs, causes signs and symptoms that may include:
- Chest pain
- 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
- 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.
What are the causes for malignant mesothelioma?
In general, cancer begins when a series of changes (mutations) happens in a cell's DNA. The DNA contains the instructions that tell a cell what to do. The mutations tell the cell to grow and multiply out of control. The abnormal cells accumulate and form a tumor.
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.
What are the treatments for malignant mesothelioma?
What treatment you undergo for mesothelioma depends on your health and certain aspects of your cancer, such as its stage and location.
Unfortunately, mesothelioma often is an aggressive disease and for most people a cure isn't possible. Mesothelioma is usually diagnosed at an advanced stage — when it isn't possible to remove the cancer through an operation. Instead, your doctor may work to control your cancer to make you more comfortable.
Discuss treatment goals with your doctor. Some people want to do everything they can to treat their cancer, even if that means enduring side effects for a small chance of an improvement. Others prefer treatments that make them comfortable so that they can live their remaining time as symptom-free as possible.
Surgeons work to remove mesothelioma when it's diagnosed at an early stage. In some cases this may cure the cancer.
Most of the time, it isn't possible to remove all of the cancer. In this situation, surgery may help to reduce the signs and symptoms caused by mesothelioma spreading in your body.
Surgical options may include:
- Surgery to decrease fluid buildup. Pleural mesothelioma may cause fluid to build up in your chest, causing difficulty breathing. Surgeons insert a tube or catheter into your chest to drain the fluid. Doctors may also inject medicine into your chest to prevent fluid from returning (pleurodesis).
- Surgery to remove the tissue around the lungs. Surgeons may remove the tissue lining the ribs and the lungs (pleurectomy). This procedure won't cure mesothelioma, but may relieve signs and symptoms.
- Surgery to remove a lung and the surrounding tissue. Removing the affected lung and the tissue that surrounds it may relieve signs and symptoms of pleural mesothelioma. If you'll be receiving radiation therapy to the chest after surgery, this procedure also allows doctors to use higher doses, since they won't need to worry about protecting your lung from damaging radiation.
- Surgery for peritoneal mesothelioma. Peritoneal mesothelioma is sometimes treated with surgery to remove as much of the cancer as possible. Chemotherapy may be used before or after surgery.
Chemotherapy uses chemicals to kill cancer cells. Systemic chemotherapy travels throughout the body and may shrink or slow the growth of a mesothelioma that can't be removed using surgery. Chemotherapy may also be used before surgery (neoadjuvant chemotherapy) to make an operation easier or after surgery (adjuvant chemotherapy) to reduce the chance that cancer will return.
Chemotherapy drugs may also be heated and administered directly into the abdominal cavity (intraperitoneal chemotherapy), in the case of peritoneal mesothelioma.
Radiation therapy focuses high-energy beams from sources such as X-rays and protons to a specific spot or spots on your body. Radiation may be used after surgery to kill any remaining cancer cells. It may also help reduce signs and symptoms of advanced cancer in situations where surgery isn't an option.
In certain situations, other treatments might be used to treat mesothelioma. Other treatments include:
- Immunotherapy. Immunotherapy uses your immune system to fight cancer. Your body's disease-fighting immune system may not attack your cancer because the cancer cells produce proteins that blind the immune system cells. Immunotherapy works by interfering with that process. This treatment might be an option if other treatments aren't working.
- Targeted therapy. Targeted therapy uses drugs that attack specific vulnerabilities in cancer cells. These drugs aren't commonly used for treating mesothelioma, but your doctor might recommend targeted therapy based on the results of tumor DNA testing.
Clinical trials are studies of new mesothelioma treatment methods. People with mesothelioma may opt for a clinical trial for a chance to try new types of treatment. However, a cure isn't guaranteed. Carefully consider your treatment options and talk to your doctor about what clinical trials are open to you. Your participation in a clinical trial may help doctors better understand how to treat mesothelioma in the future.
Clinical trials are currently investigating a number of new approaches to mesothelioma treatment, including new targeted therapy drugs and new approaches to immunotherapy.
Treatment for other types of mesothelioma
Pericardial mesothelioma and mesothelioma of tunica vaginalis are very rare. Early-stage cancer may be removed through surgery. Doctors have yet to determine the best way to treat later-stage cancers, though. Your doctor may recommend other treatments to improve your quality of life.
What are the risk factors for malignant mesothelioma?
Asbestos exposure: The primary risk factor for mesothelioma
Most mesotheliomas are thought to be related to asbestos exposure. Asbestos is a mineral that's found naturally in the environment. Asbestos fibers are strong and resistant to heat, making them useful in a wide variety of applications, such as in insulation, brakes, shingles, flooring and many other products.
When asbestos is broken up, such as during the mining process or when removing asbestos insulation, dust may be created. If the dust is inhaled or swallowed, the asbestos fibers will settle in the lungs or in the stomach, where they can cause irritation that may lead to mesothelioma. Exactly how this happens isn't understood. It can take 20 to 60 years or more for mesothelioma to develop after asbestos exposure.
Most people with asbestos exposure never develop mesothelioma. This indicates that other factors may be involved in determining whether someone gets mesothelioma. For instance, you could inherit a predisposition to cancer or some other condition could increase your risk.
Factors that may increase the risk of mesothelioma include:
- Personal history of asbestos exposure. If you've been directly exposed to asbestos fibers at work or at home, your risk of mesothelioma is greatly increased.
- Living with someone who works with asbestos. People who are exposed to asbestos may carry the fibers home on their skin and clothing. Exposure to these stray fibers over many years can put others in the home at risk of mesothelioma. People who work with high levels of asbestos can reduce the risk of bringing home asbestos fibers by showering and changing clothes before leaving work.
- A family history of mesothelioma. If your parent, sibling or child has mesothelioma, you may have an increased risk of this disease.
- Radiation therapy to the chest. If you had radiation therapy for cancer in your chest, you might have an increased risk of mesothelioma.