Learn About Mesothelioma
Mesothelioma is a rare type of cancer that develops in the pleura, a thin membrane that separates the lung from the chest wall. It generally progresses along that membrane, resulting in breathing difficulties, chest pain and fever. It often results from a prior exposure to asbestos, a type of mineral fiber used in the insulation industry. Mesothelioma can also arise, less commonly, along the abdominal cavity inner (peritoneal) lining.
- Mesothelioma is a rare type of cancer that usually arises from the pleura (lining of the lung) and less commonly the peritoneum (lining of abdomen)
- Prior exposure to asbestos is the cause of the majority of cases of mesothelioma
- Mesothelioma is not caused by smoking
- Only a minority of patients exposed to asbestos will develop the disease
- Other causes have been identified, and sometimes mesothelioma can occur in the absence of known exposure
What is Mesothelioma?
There are approximately 3,500 new cases every year in the US, a relatively small number when compared, for example, with lung cancer (220,000 new cases per year in the US). As expected, in this pattern of occupational diseases, it is more common in men than women. It is caused by exposure to asbestos in 80% of the cases. When asbestos fibers are inhaled into the lung, they can penetrate very deeply due to their small size and accumulate near the lining of the lung, or pleura. These fibers can irritate the pleura resulting in inflammation and abnormal proliferation of mesothelial (surface lining) cells, which can eventually lead to cancer many years after exposure (20-40 years on average).
The abnormally proliferating mesothelial cells produce tumor nodules on the surface of the lung and cause fluid accumulation (pleural effusion) between the lung and the chest wall, resulting in pain and shortness of breath. There are other areas in the body with a lining similar to the pleura that can also be affected, although much less commonly: the peritoneum, which is a lining found in the abdomen, the pericardium (around the heart) and, in males, the tunica vaginalis (scrotum).
How Mesothelioma Affects Your Body
Mesothelioma, unlike other cancers, tends to grow predominantly along the surface of the lung and other surfaces of the chest resulting in pain from invasion of nerves, and shortness of breath from compression of the lungs. Tumor nodules and fluid accumulates along the pleural space between the lung and the chest wall. Though mesothelioma can spread to chest lymph nodes and invade into the lung, distant dissemination, such as seen in other types of cancer, is rare. Progression of mesothelioma in the absence of effective treatment unfortunately often results in death, through mechanisms that remain poorly understood by researchers.
How Serious is Mesothelioma?
Mesothelioma is a very serious disease with a median survival of only 9 months. While extensive and promising research efforts are underway, there is currently no effective treatment for this disease. However, palliative interventions can often control debilitating symptoms and should be tailored to individual patient needs. An important point to highlight here is that there are important individual differences in how patients are affected by the disease, and some patients do much better than others.
Mesothelioma Symptoms, Causes, and Risk Factors
Mesothelioma generally occurs in individuals who have previously been exposed to asbestos, sometimes 40 to 60 years prior to the diagnosis. In most cases, mesothelioma occur at least 20 years after asbestos exposure. The extent of asbestos exposure and fiber deposition within the lung, causative for mesothelioma, is generally less than present for the causation of asbestosis or other asbestos-related lung cancers.
What are the Symptoms of Mesothelioma?
Less than 5% of individuals exposed to asbestos ultimately develop mesothelioma. Sometimes, the diagnosis is suggested on a chest- X-ray obtained for other reasons (such as concerns for pneumonia or as part of an evaluation prior to surgery for instance) in the absence of symptoms.
As the pleura is the most common site for the disease, respiratory symptoms may occur, generally late in the course of the disease, and include:
- Shortness of breath
- Chest pain, increased during breathing efforts
- Dry, persistent cough, usually without mucus production, that does not improve after several weeks or months
- Wheezing or a whistling sound during breathing
- Frequent chest cold symptoms
The progression of the cancer can also result in general symptoms described in other types of chronic illnesses, such as:
- Weight loss with low appetite
- Generalized fatigue
- Low grade fever
When other areas of the body are affected by mesothelioma, other localized symptoms may occur:
- When the peritoneum (lining on the abdomen) is involved, abdominal swelling, constipation, intestinal obstruction, and pain and nausea may occur.
- An abnormal mass or swelling may be felt in the scrotum when its lining is involved.
Rarely, the defense mechanisms of the body may try to control the disease by producing antibodies aimed at fighting the cancer that can themselves lead to symptoms, such as hypoglycemia, blood clots in the legs or the lungs, and various neurological symptoms. These symptoms are called “paraneoplastic,” which means “associated with cancer.”
What Causes Mesothelioma?
Researchers are still trying to understand what causes mesothelioma. When an exposure to asbestos has occurred in the past, the general thought is that asbestos fibers irritate the pleura over a long period of time, causing inflammation and eventually cancer.
What is Asbestos?
When an individual is exposed to asbestos, the small fibers can easily be inhaled into the lungs, increasing the risk of developing mesothelioma, lung cancer, and a type of scarring lung disease called asbestosis.
What Are the Risk Factors?
- Asbestos exposure: Asbestos is a mineral fiber that resists fire and heat, and has been used in insulation and fire-retardant materials. Most individuals who develop mesothelioma due to asbestos were exposed during their work, called an “occupational exposure.” The typical occupations associated with exposure to asbestos include miners or millers, or working with materials that contain asbestos fibers, such as electricians, plumbers, pipe-fitters, insulators, and even individuals who have remodeled older homes or lived with workers exposed to asbestos. Living in a house that contains asbestos is not generally considered to be a cause of mesothelioma when the asbestos is not directly breathed by individuals. Many individuals with increased exposure to asbestos fibers may produce benign pleural plaques, identifiable on radiographic examinations. Though these plaques do not appear to be the precursor of mesothelioma, they are often invaded by mesothelioma.
- Smoking is not a risk factor for mesothelioma, however quitting smoking is extremely important: Asbestos exposure does not only increase the risk of mesothelioma, but also of lung cancer in general. Having been exposed to asbestos and continuing to smoke results in a very high risk of developing lung cancer.
- Other types of fibers, such as erionite, are thought to be responsible for mesothelioma as well. Erionite has been identified in a specific region in Turkey called Cappadocia, and is thought to be responsible for the high rate of mesotheliomas observed in that area.
- Age: The risk of developing mesothelioma increases with age. This is due to the fact that it takes a long time for mesothelioma to develop after asbestos exposure, usually at least 20 years. This length of time from exposure to malignancy is called latency.
- Other causes have been discovered, including prior radiation therapy, particularly in patients who have received high doses of radiation therapy to the chest for cancer, such as in the treatment of lymphoma, and certain rare genetic mutations. These causes are much less common than asbestos exposure.
- Sometimes, no cause can be identified at all.
When to See Your Doctor
If you have been exposed to asbestos at work or somewhere else, have been diagnosed with frequent pneumonias, or experience the symptoms listed previously, you should consult your health-care provider.
Diagnosing and Treating Mesothelioma
Unlike breast cancer or lung cancer for example, there is no good evidence that patients who have been exposed to asbestos in the past should be screened for the disease. However, a medical consultation is necessary when there is concern for mesothelioma.
What to Expect
In general, individuals at risk and with a suspicion of mesothelioma will be referred to a specialist in lung diseases. A chest X ray is usually ordered as a first step, but a chest computed tomography scan (or chest CT) will be needed in most cases. A chest CT is a 3-dimensional X-ray which allows the specialist to visualize lung and pleural abnormalities in more details, and can identify areas of concern which should be biopsied, or sampled.
There are different ways to biopsy pleural lesions, and patients may be referred to the surgeon for a surgical biopsy, to the interventional pulmonologist for a pleuroscopy-guided biopsy, or to the interventional radiologist for a CT- or ultrasound-guided biopsy. If the diagnosis of mesothelioma is established, additional testing will be required to determine the type and extent of the disease, which will help in deciding what treatment should be considered.
How is Mesothelioma Diagnosed?
Chest X-ray: the chest X-ray may be normal, or reveal signs of prior exposure to asbestos, called pleural plaques (thickened pleura). Sometimes, the chest X-ray may reveal accumulation of fluid between the lung and the chest wall, or pleural effusion. These abnormalities, however, may only mean that the patient has been exposed to asbestos and do not establish the diagnosis of mesothelioma. A definitive diagnosis of mesothelioma cannot be rendered radiologically, it can only be ascertained by pathologic examination of tissue.
Fluid drainage, or thoracentesis: When pleural fluid is identified, the next best step is to drain the fluid with an ultrasound-guided needle aspiration. This procedure is primarily performed to exclude other causes of pleural effusions (there are many), and is not usually sufficient to establish mesothelioma. Biopsies are needed.
Chest CT scan: This test allows a more detailed examination of the chest and may allow selection of a best site to biopsy. In addition, it can determine the extent of the disease. A needle biopsy may be performed guided by CT images in the same procedure.
Biopsy: A biopsy can be obtained from the outside, with CT or ultrasound guidance, under local anesthesia, or from the inside with the use of a small camera introduced between the lung and the chest wall (thoracoscopy or pleuroscopy), under general anesthesia. Both ways have advantages and disadvantages, but usually thoracoscopy or pleuroscopy are preferred as they allow deep sampling of larger areas, often needed to establish the diagnosis with certainty. Biopsies are often difficult to interpret under the microscope and pathologists are often required to do additional testing on biopsy specimens to reach a definitive conclusion.
Staging of the disease: If mesothelioma is diagnosed, the anatomic extent of the disease needs to be determined as this will guide treatment decisions. In addition to the chest CT, a Positron-Emission Tomography scan (PET scan) is generally obtained to identify other areas involved with cancer, which may need to be biopsied as well. Biopsies of lymph nodes present between the lungs in the mediastinum are usually done as well, guided by an ultrasound probe introduced in the windpipe (trachea) and the lungs under anesthesia (bronchoscopy with endobronchial ultrasound).
Additional testing: A breathing test (pulmonary function studies) and other tests such as blood work are typically obtained to determine what kind of treatment the patient will be candidate for.
How It’s Treated
There is a currently a lot of debate on how mesothelioma should be treated, and it is important that patients with mesothelioma be referred to centers with experience and expertise in treating this rare disease. The treatment may consist of various combinations of surgery, chemotherapy and radiation therapy, depending on the type and extent of the mesothelioma, patient’s ability to tolerate treatment and, of course, patient preference. Approximately 20% of patients are found to be suitable candidates for surgery. Because mesothelioma is so rare, there has not been as much research to guide treatment decisions as in other cancers. Referral to centers of excellence with access to an expert team of physicians from different specialties (pulmonary medicine, thoracic surgery, oncology and radiation therapy) involved in diagnosis, treatment and research in mesothelioma is recommended.
Living with Mesothelioma
Mesothelioma is generally diagnosed when the progression of the disease leads to noticeable symptoms. While treatments aimed at curing the disease are limited, most of these symptoms can be effectively managed to improve quality of life.
What to Expect
Shortness of breath is a common problem that interferes with quality of life in patients with mesothelioma. Depending on individual factors, shortness of breath may be addressed by removing fluid from the pleural space with a needle, placement of a drain, or sometimes surgery. Oxygen and narcotics like morphine may also improve shortness of breath.
There may be severe pain caused by progression of the cancer into the chest wall and nerve fibers may contribute as well, and lead to poor sleep hygiene further aggravating the problem. Pain is usually treated with medications, either orally, with a patch, or intravenously. Poor nutrition and fatigue are often present due to loss of appetite, nausea, progression of the cancer, or chemotherapy.
Palliative care is a key component of the multidisciplinary care of mesothelioma. Physicians specialized in the palliative management of patients with mesothelioma could be of great value in treating symptoms and assisting patients and their loved ones about making plans for the end of life. They should become part of the team as soon as possible after the diagnosis is established.
Managing the Disease
Shortness of breath: Control of the pleural effusion is very important in improving quality of life. Several options exist including repeated needle drainage procedures, placement of a pleural drain allowing drainage of the fluid at home when needed, and interventions aimed at preventing fluid reaccumulation, typically consisting of injection of chemicals in the pleural space (pleurodesis) or surgical interventions. Pleural drains (tunneled indwelling pleural catheters) have become an attractive option due their ease of placement and use, as they do not require a hospital stay and allow patients to say at home more. Other interventions require repeated visits, in the case of repeated needle drainage, or an initial hospital stay in the case of pleurodesis or surgery.
Pain: Pain is a major problem in the daily management of mesothelioma. A stepwise approach to medications, going from lower to higher doses with increasingly efficacious medications is recommended to identify the lowest effective dose. A referral to a specialized pain service is sometimes required when the pain is difficult to control. Options include oral or intravenous medications, or skin patches allowing slow release of the medication. Palliative radiation therapy may be an effective pain management option in some circumstances.
Nutrition and active lifestyle: It is very important to maintain an active lifestyle as much as possible during the course of the disease, which is sometimes difficult when pain and shortness of breath are poorly controlled, highlighting again the importance of palliative care. Pulmonary rehabilitation with supervised exercise may be helpful. Likewise, a nutrition consultation may be beneficial when malnutrition is a concern.
Being diagnosed with mesothelioma is a major life changing event with considerable emotional, physical, familial and often financial consequences. It is very important to establish strong relationships with a team of experts able to provide support and guidance in all aspects of the management of mesothelioma.
The Mesothelioma Applied Research Foundation is a non-profit organization dedicated mesothelioma care, research and education and is a useful resource for patients and their family members. The website can be accessed at www.curemeso.org.
Questions to Ask your Doctor About Mesothelioma
The diagnosis of mesothelioma is overwhelming and affects all aspects of life in a profound way. In order to make the best use of your limited time with physicians involved in your care, it might be useful to consider the following questions, as well as questions of your own, and we would recommend actively preparing for each health-care visit by writing them down ahead of time. Important questions to ask after being diagnosed with mesothelioma may include:
- What type of mesothelioma is it? There are different kind of mesothelioma (epithelioid, sarcomatous, mixed/biphasic) which have different implications in terms of the expected course of the disease and possible treatments.
- Was the diagnosis based on tissue biopsy or simply pleural fluid analysis (general not sufficient to establish the diagnosis)?
- How extensive is the disease? Does it appear to be localized to one particular area of the pleura, or does it affect lymph nodes as well? Is the disease limited to the chest or is the peritoneum involved as well? What is the stage of the disease, and what does it mean for me?
- Should a PET scan be ordered to assess the extent of the disease? Should a bronchoscopy with lymph node biopsies be performed?
- Will my case be discussed in a multidisciplinary tumor board?
- What is the goal of the treatment you are proposing? Is the intent to cure me from the disease or manage its symptoms? How experienced is the team of physicians in managing mesothelioma?
- What are the side effects of the proposed treatment and how will it affect my quality of life?
- How long should I expect to be in the hospital? How long will the treatment last and what will it be like?
- How much will this cost for me? Can you help me identify somebody who might be able to answer these questions?
- How much experience do you have treating patients like me?
- Where can I find a center with a multidisciplinary team specialized in the management of mesothelioma? Can you recommend a particular team?
- Am I a candidate for any clinical trial?
- What are my options for palliative care to address symptomatic management of shortness of breath and pain?
You should feel comfortable asking all these questions and other ones that may be relevant to you.
Fabien Maldonado, MD, FCCP
Date Last Reviewed