Multiple myeloma is a cancer that arises from a type of white blood cell called a plasma cell. Plasma cells originate in the bone marrow and play an important role in the immune system.

Multiple myeloma develops when a normal plasma cell changes into a myeloma cell. These are cancerous cells that can multiply uncontrollably. A normal plasma cell becomes cancerous because of changes in the bone marrow or changes in a cell’s DNA (genetic mutations).

People with multiple myeloma develop tumors in more than one location in the bone marrow and sometimes outside the bone marrow. That is why the disease is called multiple myeloma.

As myeloma cells take over space in the bones where bone marrow grows, they prevent the marrow from producing essential blood cells. This includes red blood cells, which carry oxygen, and other types of white blood cells, which fight infection.

Active Myeloma and Smoldering Myeloma 

Multiple myeloma is grouped depending on whether it requires treatment or not. If the disease is causing symptoms, it is called active myeloma and treatment is required. If there aren’t any symptoms yet, it is called smoldering myeloma. Smoldering myeloma is usually closely monitored, but the disease itself is not treated until there are symptoms that it has progressed. Read more about how doctors determine the extent of the disease and whether to proceed with treatment.

Memorial Sloan Kettering provides expert care for men and women with multiple myeloma and related plasma cell diseases. Each year, we see about 400 people with newly diagnosed disease as well as an additional 200 to 300 people with newly relapsed disease, making our multiple myeloma team one of the most experienced in the nation. If you have multiple myeloma, we will work to give you the best outcome and help you achieve the highest quality of life possible.

The Role of Plasma Cells

Plasma cells produce antibodies. These are proteins that identify and fight foreign invaders. When you develop an infection, your plasma cells normally produce antibodies called immunoglobulins to help destroy it. Each immunoglobulin has a slightly different function.

Myeloma cells also produce immunoglobulins, sometimes in excessive or harmful amounts. The extra immunoglobulins may show up in the urine. Most people with myeloma have an immunoglobulin protein called Bence-Jones in their urine. This protein can be damaging to the kidneys.

Three percent of people with myeloma have nonsecretory myeloma. In this form of the disease, the cancerous plasma cells do not produce an immunoglobulin protein. There is no protein in the blood or urine, but malignant plasma cells are in the bone marrow.