Malignant Mesothelioma: Introduction

What is cancer?

Cancer is when cells in the body change and grow out of control. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body does not need them any longer.

Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby areas. They can even spread to other parts of the body (metastasis).

What is malignant mesothelioma?

Malignant mesothelioma, often just called mesothelioma, is a rare kind of cancer. It starts in the mesothelium. This is a thin lining that surrounds organs in certain parts of the body.

Understanding the mesothelium

The mesothelium is a lining that protects the outer surface of some organs. These include the lungs, stomach, and heart. It also makes fluid that helps the organs move against each other, such as when you breathe. The mesothelium has different names in different parts of the body:

  • The lining in the chest is the pleura.

  • The lining in the abdomen is the peritoneum.

  • The lining around the heart is the pericardium.

  • The lining around the testicles is the tunica vaginalis.

Mesothelioma can start in any of these linings. It’s most common in the chest. There it’s called pleural mesothelioma. The next most common site is the abdomen. There it’s called peritoneal mesothelioma.

What are the types of mesothelioma?

Mesotheliomas can also be grouped based on how the cancer cells look under a microscope:

  • The epithelioid type is the most common. It also tends to have a better outlook than the other types.

  • The sarcomatoid type tends to be harder to treat.

  • The mixed (biphasic) type has both epithelioid and sarcomatoid areas. It tends to have an outlook in between the other two types.

How mesothelioma starts and grows

Mesothelioma starts in the thin lining around certain organs. Unlike many other cancers, it usually doesn’t grow as a single large tumor. Instead, it often grows along the lining at first. This can affect how well the lining works, which can lead to symptoms. For instance, if the cancer starts in the lining around the lungs, it can eventually affect their ability to expand. This can lead to symptoms. These include shortness of breath or chest pain. Over time, the cancer can grow into nearby organs or spread to other parts of the body.

Talk with your healthcare provider

If you have questions about mesothelioma, talk with your healthcare provider. Your healthcare provider can help you understand more about this cancer.