The information that follows is an overview of this type of cancer. It is based on the more
detailed information in our document, Malignant Mesothelioma. This document and other
information can be obtained by calling 1-800-227-2345 or visiting our Web site at
www.cancer.org.
What is cancer?
The body is made up of trillions of living cells. Normal body cells grow, divide, and die
in an orderly way. During the early years of a person's life, normal cells divide faster to
allow the person to grow. After the person becomes an adult, most cells divide only to
replace worn-out, damaged, or dying cells.
Cancer begins when cells in a part of the body start to grow out of control. There are
many kinds of cancer, but they all start because of this out-of-control growth of abnormal
cells.
Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells
keep on growing and form new cancer cells. These cancer cells can grow into (invade)
other tissues, something that normal cells cannot do. Being able to grow out of control
and invade other tissues are what makes a cell a cancer cell.
In most cases the cancer cells form a tumor. But some cancers, like leukemia, rarely form
tumors. Instead, these cancer cells are in the blood and bone marrow.
When cancer cells get into the bloodstream or lymph vessels, they can travel to other
parts of the body. There they begin to grow and form new tumors that replace normal
tissue. This process is called metastasis (muh-tas-tuh-sis).
No matter where a cancer may spread, it is always named for the place where it started.
For instance, breast cancer that has spread to the liver is still called breast cancer, not
liver cancer. Likewise, prostate cancer that has spread to the bone is called metastatic
prostate cancer, not bone cancer.
Different types of cancer can behave very differently. For example, lung cancer and
breast cancer are very different diseases. They grow at different rates and respond to
different treatments. That is why people with cancer need treatment that is aimed at their
own kind of cancer.
Not all tumors are cancerous. Tumors that aren't cancer are called benign (be-nine).
Benign tumors can cause problems-- they can grow very large and press on healthy
organs and tissues. But they cannot grow into other tissues. Because of this, they also
can't spread to other parts of the body (metastasize). These tumors are almost never life
threatening.
What is mesothelioma?
Malignant mesothelioma is cancer that starts in the cells that line certain parts of the
body, especially the chest and belly (abdomen). The lining formed by these cells is called
mesothelium. These cells protect organs by making a special fluid that allows the organs
to move. For instance, this fluid makes it easier for the lungs to move during breathing.
The mesothelium has different names in different parts of the body:
· In the chest it is called the pleura.
· In the belly it is called the peritoneum.
· In the space around the heart it is called the pericardium.
Tumors of the mesothelium can be benign or they can be cancer. A cancer tumor of the
mesothelium is called a malignant mesothelioma, but this is often shortened to just
mesothelioma.
The information that follows covers only those mesotheliomas that are cancer.
Main types of mesothelioma
There are 4 main types of mesotheliomas based on how the cells look under a
microscope.
· Epithelioid: This is the most common type. It tends to have a better outlook
(prognosis) than the other types.
· Sarcomatoid (fibrous): About 1 to 2 out of 10 mesotheliomas are of this type.
· Mixed (biphasic): This type has features of the 2 types above. About 3 to 4 out of 10
mesotheliomas are the mixed type.
· Desmoplastic: These are rare.
About 3 out of 4 mesotheliomas start in the chest cavity. These are called pleural
mesotheliomas. Another 10%-20% begin in the abdomen (belly). These are called
peritoneal mesotheliomas. Those starting around the heart are very rare. This cancer can
also start in the tissue around the testicles, but this is also very rare.
detailed information in our document, Malignant Mesothelioma. This document and other
information can be obtained by calling 1-800-227-2345 or visiting our Web site at
www.cancer.org.
What is cancer?
The body is made up of trillions of living cells. Normal body cells grow, divide, and die
in an orderly way. During the early years of a person's life, normal cells divide faster to
allow the person to grow. After the person becomes an adult, most cells divide only to
replace worn-out, damaged, or dying cells.
Cancer begins when cells in a part of the body start to grow out of control. There are
many kinds of cancer, but they all start because of this out-of-control growth of abnormal
cells.
Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells
keep on growing and form new cancer cells. These cancer cells can grow into (invade)
other tissues, something that normal cells cannot do. Being able to grow out of control
and invade other tissues are what makes a cell a cancer cell.
In most cases the cancer cells form a tumor. But some cancers, like leukemia, rarely form
tumors. Instead, these cancer cells are in the blood and bone marrow.
When cancer cells get into the bloodstream or lymph vessels, they can travel to other
parts of the body. There they begin to grow and form new tumors that replace normal
tissue. This process is called metastasis (muh-tas-tuh-sis).
No matter where a cancer may spread, it is always named for the place where it started.
For instance, breast cancer that has spread to the liver is still called breast cancer, not
liver cancer. Likewise, prostate cancer that has spread to the bone is called metastatic
prostate cancer, not bone cancer.
Different types of cancer can behave very differently. For example, lung cancer and
breast cancer are very different diseases. They grow at different rates and respond to
different treatments. That is why people with cancer need treatment that is aimed at their
own kind of cancer.
Not all tumors are cancerous. Tumors that aren't cancer are called benign (be-nine).
Benign tumors can cause problems-- they can grow very large and press on healthy
organs and tissues. But they cannot grow into other tissues. Because of this, they also
can't spread to other parts of the body (metastasize). These tumors are almost never life
threatening.
What is mesothelioma?
Malignant mesothelioma is cancer that starts in the cells that line certain parts of the
body, especially the chest and belly (abdomen). The lining formed by these cells is called
mesothelium. These cells protect organs by making a special fluid that allows the organs
to move. For instance, this fluid makes it easier for the lungs to move during breathing.
The mesothelium has different names in different parts of the body:
· In the chest it is called the pleura.
· In the belly it is called the peritoneum.
· In the space around the heart it is called the pericardium.
Tumors of the mesothelium can be benign or they can be cancer. A cancer tumor of the
mesothelium is called a malignant mesothelioma, but this is often shortened to just
mesothelioma.
The information that follows covers only those mesotheliomas that are cancer.
Main types of mesothelioma
There are 4 main types of mesotheliomas based on how the cells look under a
microscope.
· Epithelioid: This is the most common type. It tends to have a better outlook
(prognosis) than the other types.
· Sarcomatoid (fibrous): About 1 to 2 out of 10 mesotheliomas are of this type.
· Mixed (biphasic): This type has features of the 2 types above. About 3 to 4 out of 10
mesotheliomas are the mixed type.
· Desmoplastic: These are rare.
About 3 out of 4 mesotheliomas start in the chest cavity. These are called pleural
mesotheliomas. Another 10%-20% begin in the abdomen (belly). These are called
peritoneal mesotheliomas. Those starting around the heart are very rare. This cancer can
also start in the tissue around the testicles, but this is also very rare.
