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 presenting with symptoms in the chest area. 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. 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. This so-called benign mesothelioma can be cured surgically.

What are the symptoms of mesothelioma?

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 restrictions on asbestos were instituted by the U.S. Occupational Safety and Health Administration (OSHA). 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 long does it take after asbestos exposure for mesothelioma to show up?

People exposed in the 1940s, '50s, '60s, and '70s are now being diagnosed with mesothelioma because of the long latency period of asbestos disease.

How is mesothelioma diagnosed?

Mesothelioma is diagnosed by pathological examination from a biopsy. Tissue is removed, placed under the microscope, and a pathologist 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:

Thoracoscopy: For pleural mesothelioma, the doctor may look inside the chest cavity with a special instrument called a thoracoscope. A cut will be made through the chest wall and the thoracoscope will be put into the chest between two ribs. This test is usually done in a hospital using an anesthetic. 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. This is called thoracentesis.

Peritoneoscopy: For peritoneal mesothelioma, the doctor may also look inside the abdomen with a special tool called a peritoneoscope. The peritoneoscope is put into an opening made in the abdomen. This test is usually done in the hospital under an anesthetic. 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. This process is 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. This is usually done 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. This can be minimized with the use of radiation to the area.

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, mesothelioma is often found 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, which is based mainly on the extent of primary tumor mass and divides mesotheliomas into four stages.

Butchart system extent of primary tumor mass

The Brigham system is the latest system and stages mesothelioma according to resectability (the ability to surgically remove the tumor) and lymph node involvement.