What Is Mesothelioma?
Mesothelioma, also called malignant mesothelioma is a type of cancer which is caused by exposure to asbestos. Mesothelioma causes tumors to develop in the layers of tissue, known as the mesothelium, surrounding vital organs. Pleural mesothelioma is the most common and affects the lungs. Peritoneal mesothelioma forms in the peritoneum or lining around the abdomen and pericardial mesothelioma, the rarest type, affects the sac surrounding the heart.
Mesothelioma is a rare type of cancer, but it is aggressive and difficult to treat. It may take decades after asbestos exposure to emerge, but once diagnosed, it has a poor prognosis and is considered fatal.
What Causes Mesothelioma?
Mesothelioma is caused by exposure to asbestos which has been inhaled or swallowed. Asbestos is a needle-like mineral substance that is mined from naturally occurring deposits in the ground. It was widely used in industrial, commercial and residential materials for its heat-absorbing and insulating properties.
During mining, manufacturing, use or destruction of asbestos and materials made with asbestos, asbestos dust is released into the air to contaminate the local area. The fibers from asbestos dust will become lodged or embedded in lung, abdominal or heart tissue. Over time, the fibers irritate the mesothelial layer surrounding these areas, leading to inflammation and scarring which may mutate and form tumors.
Most cases of mesothelioma develop in people who were exposed to asbestos in an occupational setting. Most of the people who were exposed to asbestos in occupational settings worked in industrial jobs at steel mills, power plants, shipyards, oil refineries, construction sites, factories and in the auto industry. Breathing in air that was laden with asbestos dust or consuming asbestos as dust which had settled on food at job sites has resulted in thousands of cases of workplace asbestos exposure.
In addition, family members of those workers were also exposed when asbestos-coated apparel was worn into the home. Once exposed to asbestos, the fibers worked their way into tissue around the lungs, abdomen or heart where they remained to cause inflammation and scar tissue. The needle-like shape of the asbestos fiber makes it difficult for the body to remove asbestos in the same way it would other substances.
Mesothelioma often takes years to develop. Most mesothelioma patients do not have noticeable symptoms for 20 to 50 years. Because it takes so long to develop, many people are unaware that they are at risk. The long latency period makes diagnosis difficult as the disorder may be difficult to identify, and many people are unaware or have forgotten that they were exposed to asbestos. Many mesothelioma cases are misdiagnosed as lung cancer or other types of cancer.
Asbestos was used in hundreds of commercial and consumer products until it was largely abandoned in the 1970s and 80s. Even though it is no longer used in most new consumer products, it is still used in some industrial settings. It is also still present in walls, flooring, ceiling tiles and other areas of many homes, schools and commercial buildings.
People or businesses who undertake remodeling or demolition of older buildings should ensure that no asbestos was used during construction. Buildings with asbestos products should be handled by a certified asbestos contractor for removal or containment if removal is not possible or advised.
Types of Mesothelioma
There are three major types of mesothelioma, pleural, peritoneal and pericardial. Each type varies by location and by symptoms. As the largest amount of asbestos exposure occurred by breathing asbestos-laden dust, pleural mesothelioma affecting the lungs is the most common type.
Pleural Mesothelioma – affects the mesothelial layer of the pleura which surrounds the lungs. Symptoms include:
- Chest pain
- A persistent cough
- Chest congestion
- Difficulty breathing
- Difficulty swallowing
- Unexplained or sudden weight loss
- Extreme tiredness or fatigue
- Night Sweats
Peritoneal Mesothelioma – affects the mesothelial layer of the peritoneum which lines the abdominal cavity. Symptoms include:
- Abdominal pain
- Abdominal swelling
- Bowel obstruction
- Loss of appetite
- Weight loss
- Iron deficiency anemia
- Night Sweats
Pericardial Mesothelioma – affects the mesothelial layer of the pericardium, a sac which surrounds the heart. Symptoms include:
- Irregular heartbeat or palpitations
- Chest pain
- Tightness in chest
- Difficulty breathing
- Difficulty swallowing
- Night Sweats
Based on symptoms, a doctor will conduct a physical exam, do general bloodwork and take a complete history. Exposure to asbestos should be discussed as early as possible. Additional tests may also be ordered including:
- Imaging tests: X-ray, MRI, CT and PET scans
- Blood tests: Tests for biomarkers in blood including Mesothelin, Osteopontin, HMGB1, Fibulin-2
- Biopsies: Removal of tissue via needle aspiration or surgical biopsy
In many cases, mesothelioma has been misdiagnosed as other illnesses or another type of cancer. One key element in getting the right diagnosis is a discussion of asbestos exposure, even if it is an unconfirmed possibility.
Early diagnosis will improve the prognosis and prolong life expectancy, but mesothelioma is a highly aggressive surgery with a poor prognosis. The 5-year survival rate is only about 9%. This means that 9 out of 10 mesothelioma patients will die within 5 years. Most patients who are diagnosed with mesothelioma are in the advanced stages and will not survive for more than 1 year.
Like other cancers, mesothelioma is categorized into “stages”. This helps to determine how large or widespread cancer has become, how far it has spread, how it is best treated and what prognosis the patient may have.
- The localized disease remains in the mesothelium
- No metastases and no lymph node involvement.
- Multiple treatment options with medication, radiotherapy, surgery, and other treatments
- Average life expectancy is 21+ months
- The disease has spread beyond mesothelium into surrounding tissue but is still localized
- No metastases and no lymph node involvement
- Treatment options include medication, radiotherapy, and possible surgery
- Average life expectancy about 19 months
- The disease is no longer localized, has spread beyond the region of the original tumor into deeper tissue layers and into pleural space or abdominal or chest cavity
- No metastases but possible one-side lymph node involvement
- Treatment options limited and may not include surgery
- Life expectancy about 16 months
- The disease has spread significantly and is no longer localized
- Lymph nodes on both sides and/or distant metastasis has occurred, tumors may be growing in other areas of the body
- Treatment options severely limited and the tumor cannot be addressed with surgery
- Average life expectancy likely less than 12 months
In addition to staging, there are other factors that impact survival rate, cancer location, cell type, and patient characteristics. The patient’s age and gender, overall health, history of smoking, and particular genetic characteristics may have a role in how well the patient will do. For example, younger patients, females, and non-smokers who are otherwise healthy will have a better prognosis than others.
Treatment of Mesothelioma Cancer
There are three modes of treatment that have traditionally been used for mesothelioma. In most cases, a combination of these treatments will be used. These include
- Radiation or radiotherapy
A number of factors will help determine what type(s) of treatment will be used for each patient. These factors include specifics such as age and overall health of the patient and characteristics of the mesothelioma cancer but will also include the desires of the patient in consultation with family members.
Surgery for mesothelioma is generally only viable in the early stages of cancer and is done in combination with other treatments. It is done for one of two reasons, removal of cancer and to restore function or relieve pain as much as possible. Surgery types include:
- Pleural mesothelioma
- Pleurectomy – removal of the pleura or lung lining
- Pneumonectomy – removal of the entire lung
- Extrapleural pneumonectomy – removal of the lung and surrounding tissue
- Peritoneal mesothelioma
- Peritonectomy – removal of the peritoneum or abdominal lining
- Cytoreduction or debulking – removal of tumors from organs with possible removal of the entire organ
- Pericardial mesothelioma
- Pericardectomy – removal of pericardium or heart lining
Chemotherapy can be used alone or in combination with other treatments. It is done to kill tumor cells, which will potentially shrink the tumor size and keep cancer from spreading. The most common type of chemotherapy is a treatment with the drugs Pemetrexed and Cisplatin via intravenous infusion (IV), though other drugs may be used.
In the case of peritoneal mesothelioma, another type of treatment may include HIPEC (Hyperthermic Intraperitoneal Chemotherapy) which is a “wash” of heated chemotherapy drugs infused into the peritoneal space to apply chemo directly to cancer cells.
Radiation or radiotherapy is only used in combination with chemotherapy and/or surgery. It is targeted to the tumor area to stop growth and kill some of the cancer cells to shrink tumor size. It may be done before surgery to make tumor removal easier or may be done to shrink tumor size to reduce pain and make the patient more comfortable. Radiation has a potential to damage surrounding tissue.
The patient’s general health will be taken into consideration and all treatment types have a potential risk of side effects and negative outcome. Most patients will experience fatigue, loss of appetite, nausea, and vomiting, hair loss, pain or discomfort and will have an increased risk of infection due to loss of white blood cells and immune function.
While mesothelioma is usually treated with traditional therapies first, not all patients will respond and to increase life expectancy, other treatments may be offered. In some cases, these treatments are only available as part of clinical trials or may not have been approved to treat mesothelioma but have been used on other types of cancer.
Treatments, even when new, are not often aimed at recovery or cure because of the nature of mesothelioma but are intended to increase life expectancy and improve patient comfort.
- Immunotherapy works to employ the patient’s own immune system to fight cancer. Immunotherapy is usually only available as part of a clinical study and may not be available in all areas. Immunotherapy has seen great strides in treating all types of cancer, including mesothelioma but is intended to alleviate symptoms and increase survival time. Drugs used for immunotherapy include Avastin and Keytruda.
- Virotherapy is a developing cancer treatment which uses a virus to destroy cancer cells while leaving healthy tissue intact.
- Photodynamic therapy uses a certain wavelength of light to kill cancer cells. It requires that the tumor cells were exposed to this light, making it only available for certain areas of the body. Pleural mesothelioma may be considered for treatment.
- Gene Therapy works to insert a particular gene or piece of information into the cancer cell’s DNA to alter its behavior so that it will stop dividing or self-terminate (die).
- Epigenetic therapy strives to change the instruction cancer cells are using to divide more rapidly than normal. It works on the DNA or genes of the cell to “turn off” those instructions which cause rapid cellular division.
Palliative care is aimed only at making the patient more comfortable. Palliative treatment options may integrate other modes to reduce tumor bulk but largely is intended to relieve pain and manage stress. Palliative treatment generally includes pain medication but may also employ physical therapy, meditation, yoga, acupuncture, massage and occupational or art therapy. It may also include counseling with family members.
Palliative care is done for patients who chose not to pursue “cure” and at the end stages (Stage 4) when other treatments are not effective.
Compensation for Mesothelioma Costs
Mesothelioma treatments are costly, even when covered by insurance. Because asbestos exposure is the only known cause of mesothelioma, companies who may have unnecessarily exposed their workers to asbestos may be liable for treatment and other costs. The federal government has required many companies to contribute to a national fund which may be available to assist with treatment costs and other issues.
People and loved ones of those diagnosed with mesothelioma should seek legal advice.
- Mesothelioma, Mayo Clinic (12/2017)
- Malignant Mesothelioma – HCP Version, National Cancer Institute (7/2018)
- Mesothelioma, Medline Plus (8/2018)