Mesothelioma Diagnosis
The earlier mesothelioma is detected, the better your chances are for an effective treatment. To determine whether a person has mesothelioma, doctors may use one or more of these diagnostic methods:
• Chest X ray
• CAT scan - CT or Computerized Tomography
• MRI - Magnetic Resonance Imaging
• PET scan - Positron Emission Tomography
• PFT - Pulmonary Function Test
• Transbronchial biopsy - A flexible, lighted scope is passed down the trachea to the bronchi area of the lungs.
• Thoracotomy - During surgery, the chest is opened and examined, usually between two of the lower ribs on one side.
• Thoracoscopy - A thoracoscope with a video camera is sent through an incision between the ribs.
• Centesis - Pleural, peritoneal, or pericardial fluid is drained and evaluated. This technique is used both for diagnosis and to relieve pressure, pain, and fullness in the chest or abdominal areas.
There are three types of mesothelioma.
Pleural mesothelioma is a cancer of the lining of the lung (pleura), peritoneal mesothelioma is a cancer of the lining of the abdominal cavity (peritoneum), and pericardial mesothelioma is a cancer of the lining surrounding the heart (pericardium). Sub-types (or cell types) of mesothelioma are epithelial (the most common, and considered the most amenable to treatment), sarcomatous (a much more aggressive form), and biphasic or mixed (a combination of both of the other cell types).
How is mesothelioma diagnosed?
Diagnosing mesothelioma is often difficult, because the symptoms are similar to those of a number of other conditions. Diagnosis begins with a review of the patient's medical history, including any history of asbestos exposure. A complete physical examination may be performed, including x-rays of the chest or abdomen and lung function tests. A CT (or CAT) scan or an MRI may also be useful. A CT scan is a series of detailed pictures of areas inside the body created by a computer linked to an x-ray machine. In an MRI, a powerful magnet linked to a computer is used to make detailed pictures of areas inside the body. These pictures are viewed on a monitor and can also be printed.
Your doctor will review your work history, especially whether you have worked in an industry in which you may have been exposed to asbestos.
The 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 generally are followed by a chest or abdominal X-ray, computed tomography (CT) or magnetic resonance imaging (MRI) scan. 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, called fine-needle aspiration, also may 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 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 also may need a procedure called bronchoscopy.
Staging
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 (CT) and magnetic resonance imaging (MRI), allow physicians to assess the stage of the disease and determine the most appropriate treatment. The 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.
• Stage II - The tumor is found in a stage I location, plus there is involvement of some lymph nodes in the chest.
• Stage III - The tumor has extended into the chest wall, ribs or heart, through the diaphragm or into the peritoneum (the abdominal lining). There also may be involvement of the lymph nodes.
• 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 also is 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.
Expected Duration
Once it develops, this type of cancer will continue to grow and spread until treatment is provided.
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 removed professionally 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.
Treatment
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, progression of the malignancy results in spread 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 two 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.
Types Of Treatment
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 lung and heart function. Lung function often is 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 can be aimed at long-term control (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 death within 30 days after surgery. Extrapleural pneumonectomy typically is 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 can be performed to relieve and/or control symptoms such as breathlessness, 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 can 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 limit 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 can be performed to reduce pain caused by the tumor mass or to prevent the recurrence of pleural effusion. For peritoneal mesothelioma, surgery generally is 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
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 can 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 commonly is administered after surgery in the hopes of killing remaining tumor cells. In addition, radiation therapy can be used to relieve symptoms of mesothelioma, including chest pain.
Chemotherapy
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 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.
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 also may be administered for symptom relief.
Recurrent malignant mesothelioma - There is no standard treatment for recurrent mesothelioma. Generally, treatments are considered 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 - Different combinations of chemotherapy drugs have been tried with mixed results. A recent study showed some benefit of combining cisplatin (Platinol) and gemcitabine (Gemzar). The researchers used the combination to treat 21 patients with advanced mesothelioma, of whom 47 percent showed a partial response.
• Intracavitary chemotherapy - 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.
• Gene therapy - 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 A Professional
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 usually is 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.
