- Mesothelioma is a cancer that arises from the cells lining the chest or abdominal cavities.
- Mesothelioma typically results from exposure to asbestos.
- When mesothelioma affects the chest, the doctor may look inside the chest cavity with a special instrument called a thoracoscope.
- When mesothelioma affects the abdomen, the doctor may look inside the abdomen with a special tool called a peritoneoscope.
- Health care professionals diagnose mesothelioma with a biopsy.
- The outlook for patients with mesothelioma depends on how early the disease is detected and how aggressively it is treated.
- Physicians often first detect mesothelioma late in the course of the disease, usually with a poor prognosis.
What is mesothelioma?
Mesothelioma is a rare form of cancer (malignancy) that most frequently arises from the cells lining the sacs of the chest (the pleura) or the abdomen (the peritoneum). Pleural mesothelioma is the most common form, often becoming apparent with symptoms in the chest area such as chest pain, cough, and/or shortness of breath. Shortness of breath often occurs due to a large pleural effusion (fluid in the thoracic cavity). Peritoneal mesothelioma is much less common. This can affect the organs in the abdomen, and its symptoms are related to this area of the body, that is, abdominal swelling, nausea, vomiting, and bowel obstruction. The rarest form of mesothelioma is pericardial mesothelioma, which involves the sac surrounding the heart.
There are two major cell types of mesothelioma, epithelial and sarcomatoid. Sometimes both of these cell types can be present, also referred to as biphasic. The sarcomatoid type is rarer and occurs in only about 15% of cases; it portends a poorer prognosis. In very rare cases, mesothelioma can originate from benign, non-malignant cells. Surgery cures this so-called benign mesothelioma.
What are mesothelioma symptoms?
Most people present with complaints of shortness of breath. They also can have complaints of chest pain and cough. Patients may also be asymptomatic, with the disease discovered by physical exam or an abnormal chest X-ray.
As the disease progresses, shortness of breath increases, and weight loss, decreased appetite, and night sweats can develop. Local invasion by the tumor can result in changing of voice, loss of function of the diaphragm, and symptoms specific to the area and involvement of adjacent structures.
What causes mesothelioma?
Most people with malignant mesothelioma have worked on jobs where they breathed asbestos. Usually, this involves men over 40 years of age. Others have been exposed to asbestos in a household environment, often without knowing it. The number of new cases of mesothelioma has been relatively stable since 1983, the same time that the U.S. Occupational Safety and Health Administration (OSHA) instituted restrictions on asbestos. In Europe, the number of new cases of mesothelioma continues to rise.
How much asbestos exposure does it take to get mesothelioma?
An exposure of as little as one or two months can result in mesothelioma 30 or 40 years later and in some cases, as much as 70 years later.
How do health care professionals diagnose mesothelioma?
Pathological examination from a biopsy diagnoses mesothelioma. A health care professional removes tissue. Then a pathologist places it under a microscope and makes a definitive diagnosis and issues a pathology report. This is the end of a process that usually begins with symptoms that send most people to the doctor: a fluid buildup around the lungs (pleural effusions), shortness of breath, pain in the chest, or pain or swelling in the abdomen. The doctor may order an X-ray or CT scan of the chest or abdomen. If further examination is warranted, the following tests may be done:
- Thoracentesis: This is a relatively simple procedure involving numbing the chest wall and removing some fluid for diagnosis and /or relief of symptoms from the space occupying fluid in the chest cavity. Unfortunately, it is often difficult to obtain an absolute diagnosis in differentiating adenocarcinoma of the lung, severe cellular reaction to inflammation, and mesothelium (the cells that line the chest cavity) . More invasive techniques are often required to confirm the diagnosis and develop an effective treatment strategy.
- Thoracoscopy: For pleural mesothelioma, the doctor may look inside the chest cavity with a special instrument called a thoracoscope. A doctor makes a cut through the chest wall and puts a thoracoscope into the chest between two ribs. Doctors perform this test on patients using an anesthetic in a hospital setting. If fluid has collected in your chest, your doctor may drain the fluid out of your body by putting a needle into your chest and using gentle suction to remove the fluid (a procedure called thoracentesis).
- Peritoneoscopy: For peritoneal mesothelioma, the doctor may also look inside the abdomen with a special tool called a peritoneoscope. A doctor places a peritoneoscope into an opening made in the abdomen. Physicians perform this test on a patient under an anesthetic in a hospital setting. If fluid has collected in your abdomen, your doctor may drain the fluid out of your body by putting a needle into your abdomen and using gentle suction to remove the fluid (a process called paracentesis).
- Biopsy: If abnormal tissue is found, the doctor will need to cutout a small piece and have it looked at under a microscope. Doctors do this during the thoracoscopy or peritoneoscopy, but can be done during surgery. Unfortunately, in some cases, tumor cells can grow along the tract where the biopsy is taken, although this remains unproven. Radiation to the area minimizes this risk.
What is the prognosis for mesothelioma?
Like most cancers, the prognosis for this disease often depends on how early it is diagnosed and how aggressively it is treated. Unfortunately, oftentimes health care professionals find mesothelioma at a stage in which a cure is unobtainable. Many will succumb to the disease within one year of diagnosis.
Mesothelioma treatment options (traditional and new treatments being studied)
Treatment options are determined by the stage of mesothelioma (the extent to which the tumor has spread in the body). There are three staging systems currently in use, and each one measures somewhat different variables.
The oldest staging system and the one most often used is the Butchart system, based mainly on the extent of primary tumor mass and divides mesotheliomas into four stages.
Butchart system extent of primary tumor mass
- Stage I: Mesothelioma is present in the right or left pleura and may involve the diaphragm on the same side.
- Stage II: Mesothelioma invades the chest wall or involves the esophagus, heart, or pleura on both sides. Lymph nodes in the chest may also be involved.
- Stage III: Mesothelioma has penetrated through the diaphragm into the lining of the abdominal cavity or peritoneum. Lymph nodes beyond those in the chest may also be involved.
- Stage IV: There is evidence of metastasis or spread through the bloodstream to other organs.
TNM system: variables of T (tumor), N (lymph nodes), and M (metastasis)
- Stage I: Mesothelioma involves right or left pleura and may have spread to the lung, pericardium, or diaphragm on the same side. Lymph nodes are not involved.
- Stage II: Mesothelioma has spread from the pleura on one side to nearby lymph nodes next to the lung on the same side. It may also have spread into the lung, pericardium, or diaphragm on the same side.
- Stage III: Mesothelioma is now in the chest wall, muscle, ribs, heart, esophagus, or other organs in the chest on the same side with or without spread to lymph nodes on the same side as the primary tumor.
- Stage IV: Mesothelioma has spread into the lymph nodes in the chest on the side opposite the primary tumor, extended to the pleura or lung on the opposite side, or directly extended into organs in the abdominal cavity or neck. Any distant metastases is included in this stage.
The Brigham system is the latest system and stages mesothelioma according to resectability (the ability to remove the tumor surgically) and lymph node involvement.
Brigham system: variables of tumor resectability and nodal status
- Stage I: resectable mesothelioma and no lymph node involvement
- Stage II: resectable mesothelioma but with lymph node involvement
- Stage III: unresectable mesothelioma extending into chest wall, heart, or through diaphragm, peritoneum; with or without extrathoracic lymph-node involvement
- Stage IV: distant metastatic disease
What is the treatment for mesothelioma?
There are three traditional kinds of treatment for patients with malignant mesothelioma. Often physicians combine two or more of these in the course of treatment:
- surgery (taking out the cancer),
- radiation therapy (using high-dose X-rays or other high-energy rays to kill cancer cells), and
- chemotherapy (using drugs to fight the cancer).
Surgery: There are several types of surgery used in treating mesothelioma.
- A pleurectomy is the removal of part of the chest or abdomen lining and some of the tissue around it.
- Depending on how far the cancer has spread, physicians may remove a lung in an operation called a pneumonectomy.
- In an extrapleural pneumonectomy, a doctor removes the lung along with the lining and diaphragm (the muscle that helps you breathe) on the affected side. In this surgery, the lining around the heart is also removed.
- Sometimes a physician performs a pleurectomy/decortication. In this surgery, a doctor removes the lining of the lung along with as much of the tumor as possible.
- Determining appropriate candidates for surgery can be difficult. Staging of a cancer is the process that determines how extensive the cancer is, or how far it has grown and spread. Often, staging procedures such as mediastinoscopy (examining the central part of the chest through a tube) or peritoneoscopy (examining the inside of the abdominal cavity with a tube) are necessary to determine the extent of disease. Clinical staging often underestimates true pathological staging (the amount of tumor found when biopsied). CT scanning, PET/CT, and or MRI can help in the staging process.
- In choosing candidates for surgery, the individual’s underlying physical condition matters. Diseases of other organ systems have a negative impact on survival. The more localized the disease (low stage) the better the prognosis. The cell type also affects prognosis; tumors with an epithelioid cell types have better outcomes.
Radiation therapy uses high-energy X-rays to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external radiation therapy) or from putting materials that produce radiation (radioisotopes) through thin plastic tubes in the area where the cancer cells are (internal radiation therapy).
If fluid has collected in the chest or abdomen, your doctor may drain the fluid out of your body by putting in a needle into the chest or abdomen and using gentle suction to remove the fluid. If a doctor removes fluid from the chest, this is called thoracentesis. If a physician removes fluid from the abdomen, this is called paracentesis. Your doctor may also put drugs through a tube into the chest to prevent more fluid from accumulating.
Health care professionals administer adjuvant radiation in a manner to avoid exposure of the opposite lung to radiation and its potential side effects.
Chemotherapy is the use of drugs to kill cancer cells. Health care professionals administer chemotherapy by pill, or it may be put into the body by a needle in the vein or muscle. Often, a platinum-based chemotherapy (cisplatin or carboplatin) drug is given along with a second agent, pemetrexed. The side effects can be quite toxic, therefore they are used in people who are physically well enough to tolerate these side effects.
Chemotherapeutic agents can be administered either systemically (through the bloodstream) or intrapleurally (in the pleural cavity). When it is administered intrapleurally, the treatment is localized at the site of the tumor. These drugs are generally very toxic and you should discuss their use very carefully with your physician.