Malignant Mesothelioma – Pleural, Peritoneal & Pericardial

Malignant Mesothelioma Explained
Malignant mesothelioma is a rare form of cancer that is diagnosed in approximately 3,000 people each year. The disease usually affects the pleura, which is the membrane that lines the chest cavity and the lungs. It may also affect the peritoneum, which is the lining of the abdominal cavity, and (very rarely) the pericardium, which is the lining around the heart. The pleura, peritoneum and pericardium each have two layers, which are separated by a lubricating fluid that allows the internal organs to move easily. About 70 percent of all cases of malignant mesothelioma can be attributed to exposure to asbestos, a naturally occurring mineral that is used in a variety of industries. A small percentage of the remaining cases have been linked to exposure to a particular type of radiation or to a mineral silicate called zeolite. In some cases, the cause is unknown.

People exposed to asbestos for a long time or exposed to high levels have an increased risk of developing malignant mesothelioma, but even people exposed for a very short time can develop this disease. The disease occurs a minimum of 15 years (typically 20 to 40 years) after asbestos exposure. The average age at diagnosis is 50 to 70 years. More men than women are affected, probably because men are more likely to have worked in the industries that use asbestos.

Three main types of malignant mesothelioma are recognized: epithelial, sarcomatoid and mixed. The epithelial type is the most common. All three types have the same treatment options.

Malignant Mesothelioma Symptoms
About 90 percent of patients who are diagnosed with malignant mesothelioma have chest pain and shortness of breath as the first symptoms of the disease. These symptoms are generally caused by pleural effusion (collection of fluid in the chest), not by mesothelioma itself. Individuals with mesothelioma that originates in the peritoneum (abdominal lining) may have abdominal pain and swelling due to an accumulation of fluid in the abdominal cavity. Other possible symptoms include fever, sweating, cough, fatigue and unexplained weight loss.

Malignant Mesotheloima Diagnosis
Diagnosis of malignant mesothelioma begins with a thorough medical history to document the patient’s symptoms and any possible asbestos exposure, followed by a complete physical examination. These steps are generally followed by a chest or abdominal X-ray, computed tomography or magnetic resonance imaging . The imaging studies allow the physician to assess the size, location and extent of the tumor in the chest or abdomen.

If fluid is present in the pleura or peritoneum, a thin needle may be used to collect a small sample of the fluid for examination (this procedure is called fine-needle aspiration). This technique may also be used to drain the fluid to relieve symptoms such as chest pain and shortness of breath that can result from an effusion. Occasionally, mesothelioma can be diagnosed with this fluid sample alone, but usually a tissue sample (biopsy) is required. The tissue sample can be obtained with a long needle via thoracoscopy (for a pleural tumor) or via laparoscopy (for an abdominal tumor). In both procedures, a tubelike instrument inserted through a small incision allows the physician to view the tumor and collect a tissue sample. Patients suspected of having pleural mesothelioma may also need a procedure called bronchoscopy .

If a larger sample of tissue is needed, a surgeon may open the chest cavity (called thoracotomy) or the abdominal cavity (called laparotomy).

Staging of Malignant Mesothelioma

Once the diagnosis of malignant mesothelioma has been confirmed, the next step is determining the extent of the disease (called staging). Imaging studies, such as computed tomography and magnetic resonance imaging, allow physicians to assess the stage of the disease and determine the most appropriate treatment. The Butchart stages of malignant mesothelioma are:

Mesothelioma Stage I – The tumor is found in the pleura with or without some involvement of the lung, pericardium (lining of the heart) or diaphragm.
Mesothelioma Stage II – The tumor is found in a stage I location, plus there is involvement of some lymph nodes in the chest.
Mesothelioma Stage III – The tumor has extended into the chest wall, ribs or heart, through the diaphragm or into the peritoneum (the abdominal lining). There may also be involvement of the lymph nodes.
Mesothelioma Stage IV – The tumor has spread through the bloodstream to distant sites (that is, it has metastasized).
Recurrent Mesothelioma – The tumor has recurred after treatment.
Stage I is also called localized disease, whereas stages II to IV are called advanced disease. Stage I disease generally has the best prognosis, particularly when the tumor is of the epithelial type and the patient is younger than 55.

Mesothelioma Prevention
To reduce your risk of malignant mesothelioma, you should reduce your exposure to asbestos. Because there is no "safe" level of asbestos exposure, any asbestos exposure is too much. Especially if you have an older home, check for areas of exposed asbestos-containing insulation or other areas of deteriorating asbestos. These areas must be professionally removed or safely sealed off. Workers who routinely deal with asbestos-containing materials should use approved measures to limit their exposure and to keep from bringing asbestos dust home on their clothing.

Medical Treatment of Malignant Mesothelioma
The treatment of malignant mesothelioma has proven difficult. Because the disease begins in the pleura and peritoneum, which are the membranes surrounding the chest cavity and abdominal cavity, respectively, mesothelioma almost always spreads to the underlying organs. The tumor spread makes complete surgical removal nearly impossible. Furthermore, the effectiveness of different treatments has been difficult to evaluate in large treatment trials because there are relatively few cases of malignant mesothelioma.

Although the general prognosis for malignant mesothelioma is not encouraging – on average, patients live about one year after diagnosis – an early diagnosis and aggressive treatment can improve survival – up to 2 years in almost 50 percent of cases and five years (or longer) in 20 percent. Some of the factors that affect prognosis are the type of mesothelioma, the stage of disease at diagnosis, the patient’s age and the patient’s overall health. The prognosis is best when the mesothelioma is the epithelial type and stage I and the patient is younger than 55 and does not have an underlying illness.

Types of Available Medical Treatment, Drug Therapy, Chemotherapy and Surgery for Malignant Mesothelioma Victims

The primary treatment options for malignant mesothelioma are surgery, radiation therapy and chemotherapy.

Surgery — Before any surgery is considered for the treatment of malignant mesothelioma, the patient’s overall health is carefully evaluated. Tests are performed to make sure the patient has no metastatic disease (cancer spread to distant sites) and to evaluate the patient’s pulmonary (lung) and cardiac (heart) function. Pulmonary function is often compromised in patients with pleural mesothelioma for several reasons. The pleural effusion (fluid collection) and the tumor mass caused by mesothelioma can compress the lung. Also, the patient’s exposure to asbestos may have decreased lung function, which also decreases with age. In addition, some patients have a history of smoking cigarettes, which further decreases lung function.

Surgery for malignant mesothelioma may be aimed at cure (aggressive surgery) or relief of symptoms (palliative procedures).

Aggressive surgery – Extrapleural pneumonectomy involves removal of the pleura, the lung, the diaphragm and the pericardium. The intent of this very aggressive, complicated surgery is to remove as much of the tumor as possible. Not all centers will perform this procedure because of its complexity and because it carries a high risk of postoperative mortality (death within 30 days after surgery). Extrapleural pneumonectomy is typically performed only in younger patients in good overall health with stage I disease. Patients are evaluated carefully to determine their ability to tolerate the surgery. Palliative procedures – When malignant mesothelioma is advanced, palliative procedures may be performed to relieve and/or control symptoms such as breathlessness and pain, which are caused by effusion (fluid collection) or by the tumor compressing the lung or other organs. These procedures do not aim to cure the disease.

Thoracentesis may be used to treat effusion in pleural mesothelioma. A needle is inserted into the chest to drain the fluid, relieving breathlessness and pain. Talc may be introduced into the pleura to prevent recurrence of the effusion. Similar procedures are used to treat ascites (fluid collection) in peritoneal mesothelioma.

Pleurectomy / decortication is the surgical removal of the pleura. This procedure may be performed to reduce pain caused by the tumor mass or to prevent the recurrence of pleural effusion. For peritoneal mesothelioma, surgery is generally aimed at relieving symptoms, such as recurrent ascites or bowel obstruction. As with pleural mesothelioma, complete surgical removal of the entire tumor is unlikely.
Radiation Therapy – Mesothelioma

Because of the location of malignant mesothelioma, it is extremely difficult to deliver high enough doses of radiation to kill the tumor without damaging the surrounding organs. Lower doses of radiation may result in some reduction in the disease, but it is unclear whether this reduction actually results in longer survival than does no treatment.

Using radiation therapy after surgery has not been shown to improve survival. However, because surgery is very unlikely to remove the entire tumor, radiation is commonly administered after surgery in the hopes of killing remaining tumor cells. In addition, radiation therapy can be used to relieve symptoms of mesothelioma, including pain and shortness of breath.

Chemotherapy – Mesothelioma

Chemotherapy – the use of medications to treat cancer – has had disappointing results in the treatment of malignant mesothelioma. Some chemotherapy drugs have a partial effect in some patients. Combination chemotherapy (using more than one drug at the same time) may be given in an attempt to improve response. Some combinations have shown some promise, and some new medications are being tried.

Like radiation therapy, chemotherapy may be administered after surgery in an attempt to kill cancer cells that could not be removed during the procedure.

Treatment by Mesothelioma Stage

Pleural mesothelioma can be treated according to stage; there are no standard treatment options by stage for peritoneal mesothelioma.

Stage I (localized) mesothelioma – If a patient wants aggressive treatment and is deemed fit to undergo surgery, some centers may perform an extrapleural pneumonectomy. Another surgical option is pleurectomy/decortication, which is sometimes performed to alleviate some of the symptoms of mesothelioma. Both of these procedures may be followed by radiation therapy or chemotherapy. Alternatively, radiation therapy may be used alone, without surgery, for the relief of symptoms.

Stages II, III and IV (advanced) mesothelioma – Pleurectomy/decortication may be performed to relieve symptoms in pleural mesothelioma. Other procedures such as thoracentesis may be performed to drain pleural effusions and prevent them from recurring. Radiation therapy and/or chemotherapy may also be administered for symptom relief.

Recurrent malignant mesothelioma – There is no standard treatment for recurrent mesothelioma; generally, treatments are chosen that were not used in the first treatment attempt.

Clinical Trials And Future Treatments

New treatments for malignant mesothelioma (and possible preventive measures, such as a vaccine) are being evaluated in clinical trials, and the future holds some promise. Clinical trials are research studies that evaluate new treatments for safety and effectiveness. There are no guarantees that a new treatment will work, and there are some risks; however, a clinical trial is not undertaken unless the researchers believe the treatment may have some value.

Here are some of the treatments for malignant mesothelioma that are being evaluated:

Combination chemotherapy for mesothelioma – Different combinations of chemotherapy drugs have been tried with mixed results. A recent study showed some benefit of combining cisplatin and gemcitabine. The researchers used the combination to treat 21 patients with advanced mesothelioma, of whom 47 percent showed a partial response.

Medications & Mesothelioma – One study showed that lovastatin, a cholesterol-lowering drug, may be useful for the treatment of malignant mesothelioma. The drug was found to induce apoptosis (cell death) in mesothelioma cells, which may increase the effectiveness of radiation therapy and chemotherapy.

Intracavitary Chemotherapy for Mesothelioma – Instilling chemotherapy drugs directly into the pleural or peritoneal space is being researched because of its advantage over traditional chemotherapy: because the drug is instilled directly into the cavity, much greater doses can be given to patients without causing severe side effects. Some studies have shown this therapy to result in control of effusions and reduced tumor size.

Brachytherapy (intracavitary radiation therapy) – In this treatment, a radioactive substance is placed directly into the pleural or peritoneal space.

Multimodality therapy – Any combination of surgery, radiation therapy and chemotherapy is multimodality therapy. For example, researchers have combined surgery with intracavitary radiation or chemotherapy and then administered radiation or chemotherapy afterward. Some physicians are administering chemotherapy before surgery in an attempt to decrease the size of the tumor.

Gene therapy & Mesothelioma – In this approach, a virus that has been genetically altered is introduced into the tumor. The virus infects the tumor cells and makes them vulnerable to anticancer drugs.

Immunotherapy – Treatments that stimulate the body’s immune system to fight cancer cells are called immunotherapy.

Photodynamic therapy – In this treatment, drugs that are sensitive to light are taken up by the tumor cells, which are then exposed to light.
When To Call Your Doctor
Call your doctor promptly if you have any of the symptoms of lung cancer, especially if you have worked in an industry with high exposure to asbestos.

Prognosis
Malignant mesothelioma is usually advanced by the time it is diagnosed and thus has a poor prognosis: on average, the survival time after diagnosis is about one year. However, several factors affect prognosis, including the extent of the tumor and the age and health of the patient. In some cases, survival time can be increased with early detection and aggressive treatment, and improved treatments should be available in the near future.

Additional Information and Links for Malignant Mesothelioma
For more information about lung cancer, you can contact:

National Cancer Institute (NCI)
Building 31, Room 10A03
31 Center Drive, MSC 2580
Bethesda, MD 20892-2580
Phone: (800) 4-CANCER
Phone: (301) 435-3848
www.nci.nih.gov

American Cancer Society
1599 Clifton Road, N.E.
Atlanta, GA 30329-4251
Phone: (800) ACS-2345
www.cancer.org

American Lung Association
National Office
1740 Broadway
New York, NY 10019
Phone: (800) LUNG-USA
www.lungsusa.org

The National Heart, Lung and Blood Institute
6701 Rockledge Drive
P.O. Box 30105
Bethesda, MD 20824-0105
Phone: (301) 592-8573
NHLBIinfo@rover.nhlbi.nih.gov
www.nhlbi.nih.gov

U.S. Environmental Protection Agency (EPA)
401 M Street, SW
Washington, DC 20460-0003
Phone: (202) 260-2090
www.epa.gov

If you work with asbestos, you can access the website of the National Institute for Occupational Safety and Health (NIOSH) for more information about protecting yourself and your family. The NIOSH is part of the federal government’s Centers for Disease Control and Prevention (CDC).

National Institute for Occupational Safety and Health
Address line 2
Phone: (800) 35-NIOSH
Fax: (513)533-8573
www.cdc.gov/niosh

 


 

 

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