Malignant Mesothelioma – Pleural, Peritoneal & Pericardial
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.
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:
Stage I – The tumor is found in the pleura with or without some
involvement of the lung, pericardium (lining of the heart) or diaphragm.
Treatment 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.
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.
therapy – In this treatment, drugs that are sensitive to light
are taken up by the tumor cells, which are then exposed to light.
and Links for Malignant Mesothelioma
American Lung Association
The National Heart,
Lung and Blood Institute
Protection Agency (EPA)
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).
for Occupational Safety and Health