Booklet: What You Need to Know about Multiple Myeloma

What Is Multiple Myeloma?

Multiple myeloma is a type of cancer. It affects certain white blood cells called plasma cells. To understand multiple myeloma, it is helpful to know about normal cells, especially plasma cells, and what happens when they become cancerous.

Normal Cells

The body is made up of many kinds of cells. Each type of cell has special functions. Normal cells are produced in an orderly, controlled way as the body needs them. This process keeps us healthy.

Plasma cells and other white blood cells are part of the immune system, which helps protect the body from infection and disease. All white blood cells begin their development in the bone marrow, the soft, spongy tissue that fills the center of most bones. Certain white blood cells leave the bone marrow and mature in other parts of the body. Some of these develop into plasma cells when the immune system needs them to fight substances that cause infection and disease.

Plasma cells produce antibodies, proteins that move through the bloodstream to help the body get rid of harmful substances. Each type of plasma cell responds to only one specific substance by making a large amount of one kind of antibody. These antibodies find and act against that one substance. Because the body has many types of plasma cells, it can respond to many substances.

Cancer

Cancer is a group of diseases with one thing in common: Cells become abnormal and are produced in large amounts. Cancerous cells interfere with the growth and functions of normal cells. In addition, they can spread from one part of the body to another.

Myeloma Cells

When cancer involves plasma cells, the body keeps producing more and more of these cells. The unneeded plasma cells--all abnormal and all exactly alike--are called myeloma cells.

Myeloma cells tend to collect in the bone marrow and in the hard, outer part of bones. Sometimes they collect in only one bone and form a single mass, or tumor, called a plasmacytoma. In most cases, however, the myeloma cells collect in many bones, often forming many tumors and causing other problems. When this happens, the disease is called multiple myeloma. This booklet deals mainly with multiple myeloma.

(It is important to keep in mind that cancer is classified by the type of cell or the part of the body in which the disease begins. Although plasmacytoma and multiple myeloma affect the bones, they begin in cells of the immune system. These cancers are different from bone cancer, which actually begins in cells that form the hard, outer part of the bone. This fact is important because the diagnosis and treatment of plasmacytoma and multiple myeloma are different from the diagnosis and treatment of bone cancer.)

Because people with multiple myeloma have an abnormally large number of identical plasma cells, they also have too much of one type of antibody. These myeloma cells and antibodies can cause a number of serious medical problems:

• As myeloma cells increase in number, they damage and weaken bones, causing pain and sometimes fractures. Bone pain can make it difficult for patients to move.
• When bones are damaged, calcium is released into the blood. This may lead to hypercalcemia--too much calcium in the blood. Hypercalcemia can cause loss of appetite, nausea, thirst, fatigue, muscle weakness, restlessness, and confusion.
• Myeloma cells prevent the bone marrow from forming normal plasma cells and other white blood cells that are important to the immune system. Patients may not be able to fight infection and disease.
• The cancer cells also may prevent the growth of new red blood cells, causing anemia. Patients with anemia may feel unusually tired or weak.
• Multiple myeloma patients may have serious problems with their kidneys. Excess antibody proteins and calcium can prevent the kidneys from filtering and cleaning the blood properly.

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