Malignant mesothelioma, a type of cancer that affects the linings of the body's major organs, is notorious as a destructive cancer that leaves its victims with a very poor prognosis. Victims are generally given a median survival time of six to 12 months after diagnosis. This is partly because mesothelioma has no early symptoms at all, meaning victims often don't have any reason to suspect the disease until it has taken root. For decades after significant exposure to asbestos, victims feel fine. It's only 10 to 60 years after contact with the carcinogen that patients begin to notice anything wrong. Early symptoms of mesothelioma include:

• shortness of breath (dyspnea)
• pain in one side of the chest, the back or the abdomen, often with swelling
• a persistent cough
• unexplained weight loss
• nausea
• trouble with swallowing
• unexplained fever

Types of Mesothelioma

There are three subtypes of mesothelioma. The most common is pleural mesothelioma, which is cancer of the pleura -- the tissues lining the lungs themselves and the chest cavity. Because the disease lies near or in the lungs, this is the type of mesothelioma that causes swelling and fluid buildup in the chest. Pleural mesothelioma tends to concentrate in one side of the lungs; symptoms may also concentrate on that side. Other symptoms specific to pleural mesothelioma include:

• fatigue
• anemia
• coughing up blood
• in severe cases, collapse of the lung (pneumothorax)

A second type of mesothelioma is peritoneal mesothelioma, which is cancer of the tissues lining the abdomen. This is the type of mesothelioma that causes abdominal pain and swelling due to fluid buildup, and other symptoms related to digestion. Specific symptoms of peritoneal mesothelioma include:

• unexplained weight loss
• weakness (cachexia)
• an abdominal mass
• obstructed bowels
• problems with blood clotting
• fever
• iron deficiency (anemia)

The final and least common type of mesothelioma is pericardial mesothelioma -- cancer of the tissues that line the heart. This is very, very rare, found in fewer than 10% of mesothelioma patients. But because the cancer is located next to the heart, treatment for pericardial mesothelioma is troublesome and dangerous. In addition to the common symptoms, signs specific to pericardial mesothelioma include:

• chest pain and swelling in the chest
• irregular heartbeat
• heart palpitations

In advanced cases of malignant mesothelioma, symptoms might include internal bleeding, blood clots, low blood sugar and jaundice in the eyes and skin. Other symptoms vary according to which subtype type of mesothelioma a patient has.

Doctors divide cases of mesothelioma into categories that reflect how far the cancer has spread into the body. If mesothelioma is localized, that means the tumors are all in one place; in advanced mesothelioma, the cancer has spread, or metastasized, into other parts of the body. Doctors also assign four "stages" to the disease:

• Stage I: Localized mesothelioma that exists only in the lungs, the diaphragm or the pericardial lining.
• Stage II: Advanced mesothelioma that has spread into the lymph nodes of the chest.
• Stage III: Advanced mesotheioma that has spread into the wall of the chest, the center of the chest, the lining of the heart and the diaphragm. Stage III malignant mesothelioma may or may not have spread to the lymph nodes.
• Stage IV: Advanced mesothelioma that has spread far from the chest and abdomen into other organs.

Generally speaking, only Stage I and some Stage II patients are candidates for surgery and other treatments intended to cure malignant mesothelioma. While some experimental treatments may be available to other patients, treatment for Stage III and beyond generally focuses on making the patient more comfortable.

Mesothelioma Misdiagnosis

When symptoms of malignant mesothelioma do show up, they show up so long after asbestos exposure that victims, and their doctors, may not suspect mesothelioma at first. Complicating matters, these early symptoms often seem similar to symptoms of more common diseases. Doctors may decide that the symptoms come from a lingering cold, emphysema, pneumonia or another, less serious, lung problem. Mesothelioma symptoms that are not clearly related to the lungs, such as an obstructed bowel, a fever or yellow jaundice, may further complicate the diagnosis. Because mesothelioma patients tend to be older men, statistically speaking, doctors may be thrown off by lifestyle-related factors like smoking (which does not cause mesothelioma), diet or exposure to pollution. And finally, the tumors caused by mesothelioma are easy to mistake for tumors of another, more common, type of cancer such as pleural adenocarcinoma.

For all of these reasons, mesothelioma may be misdiagnosed or undiagnosed at first, even when the patient is seeing a doctor regularly. This is unfortunate, because mesothelioma patients have a much better prognosis when their disease is caught early. Fortunately, because mesothelioma is caused only by exposure to asbestos, patients can help ensure they're treated quickly by making sure their doctors know about their history with the carcinogenic mineral. (In fact, one way doctors diagnose mesothelioma is by asking about the patient's history of asbestos exposure.) People who were occupationally or environmentally exposed to asbestos earlier in life -- even much earlier -- should be aware of these symptoms and bring up the exposure, even if their doctors do not. And people at high risk for asbestos exposure should make sure they're well-protected according to the strict federal standards governing asbestos, because mesothelioma is 100% preventable.

Diagnosis

Generally, if doctors suspect mesothelioma, they will first ask about the patient's history of exposure to asbestos and perform a physical examination. They will probably follow this up with an internal test that checks for the internal signs of mesothelioma, like fluid buildup inside the lungs or tumors. These tests could be one or more of the following:

• X-rays
• CT scan
• MRI
• blood tests
• pulmonary function tests, which measure how well the patient can breathe

If those tests show signs of mesothelioma, doctors will do tests to see how far the cancer has progressed. They may drain fluid from the chest or abdomen, then test that fluid for cancer cells; or do a biopsy -- surgery aimed at finding and removing suspected cancer cells for testing.