Mesothelioma is a very uncommon form of cancer that has been proven to be almost always caused by the inhalation of asbestos particles. Mesothelioma, is extremely aggressive and usually spreads throughout a person's body very quickly once it develops. Therefore, after it is detected in a person's body, it normally spreads and aggressively invades a person's vital organs and tissues - and possibly other areas within the body - within several months. Left untreated, mesothelioma patients generally do not face a very positive long-term prognosis.

Mesothelioma shows up inside the body in the form of tumors. The tumors can appear in any place or on any organ that has a mesothelium covering. Sometimes the tumors are detected and then determined to be benign, or non-cancerous. Non-cancerous mesothelioma tumors are usually treated, but not necessarily in the same manner as cancerous ones.

Chances are, if a person with mesothelioma tumors was ever exposed to or inhaled asbestos particles at any time in their life, the tumors will be malignant, or cancerous. The only definitive way to determine if the mesothelioma is benign or malignant is to have a biopsy.

Once a malignant mesothelioma tumor has been detected, tested, and determined to be malignant, other malignant tumors are likely to appear on other internal organs. This type of "spreading" of tumors is referred to as metastasizing. If mesothelioma is discovered in the chest cavity, for example, tumors may begin appearing in places other than the original site. There is no way to determine on which organs the tumors will pop up after the original diagnosis.

There are several types of malignant mesothelioma, but three of them are the most common. The most common out of these three is called "Epithelial." Luckily, epithelial, is the type of mesothelioma that responds best to treatment. All three types are generally treated the same way in terms of surgery, radiation and chemotherapy.

In most cases, malignant mesothelioma is discovered in a person's chest cavity. The second most common place for tumors to exist at time of diagnosis is the abdomen. The least common place for tumors to be found upon original discovery is in the heart.
When tumors exist in the chest cavity, they are called "Pleural Mesotheliomas," when they are found in the abdomen, they are called, "Peritoneal Mesotheliomas," and when they are discovered in the heart, they are called, "Pericardial Mesotheliomas."

The mesothelium is a two layer covering that encases the body's internal organs and allows them to sit next to other organs and tissues without them rubbing or causing friction between each other. In other words, the mesothelium membrane provides the outer layer of the organs with a lubricating fluid so that they can glide along side of each other. The heart and lungs, for example, constantly expand and contract, and the mesothelium membrane allows these organs to move without any sort of friction.

Depending on the location in the body, or the organ which it is surrounding, the mesothelium is referred to by different names. When referring to the mesothelium that covers the organs in a person's abdomen, the mesothelium is called, "The Peritoneum." The mesothelium that covers the organs in the chest or the lungs is called, "The Pleura." The mesothelium membrane that covers the heart is called "The Pericardium."

When a person develops mesothelioma, tumors begin to grow on the mesothelium. Tumors can form and appear on the peritoneum, the pleura, and/or the pericardium mesothelium. When tumors form, it is a sign that the cells that make up the mesothelium are dividing out of control and out of their normal order. Once the cancer has started, it commonly spreads to other mesothelium areas within the body, and it can also metastasize to tissues that surround the affected organs.