Cancer is a group of many related diseases. All cancers begin in cells,
the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place. Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor
Tumors can be benign or malignant.
Benign tumors are not cancer.
Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer.
They are generally more serious. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original (primary
) tumor to form new tumors in other organs. The spread of cancer is called metastasis.
A layer of specialized cells called mesothelial cells lines the inside of the chest, the abdomen, and the space around your heart. These cells also cover the outer surface of many internal organs. The lining formed by these cells is called mesothelium.
The mesothelium helps protect your organs by making a special lubricating fluid that allows organs to move. The mesothelium has different names in different parts of the body. In the space around the heart, it is called the pericardium
. In the chest, the pleura
. And, in the abdomen, it is called the pleura.
A cancerous tumor of the mesothelium is called a malignant mesothelioma
. This is normally shortened to just mesothelioma. Mesotheliomas generally start in four sections of the body:
- These start in the chest and comprise nearly 75% of mesothelioma cases.
- These begin in the abdomen and comprise nearly 25% of mesothelioma cases.
- These start in the covering around the heart and are very rare.
Mesotheliomas of the Tunica Vaginalis
- These start in the covering of the layer of the testicles and are very rare.
It is important not to confuse benign mesothelioma tumors (Adenomatoid tumors, Benign Cystic Mesothelioma and Solitary Fibrous Tumor of the Pleura) as these are generally removed by surgery and no further treatment is necessary. It is also important not to confuse mesothelioma with lung cancer.