Multiple myeloma

DEFINITION

Multiple myeloma is a cancer that forms in a type of white blood cell called a plasma cell. Plasma cells help you fight infections by making antibodies that recognize and attack germs.

Multiple myeloma causes cancer cells to accumulate in the bone marrow, where they crowd out healthy blood cells. Rather than produce helpful antibodies, the cancer cells produce abnormal proteins that can cause kidney problems.

Treatment for multiple myeloma isn’t always necessary. If you’re not experiencing signs and symptoms, you may not require treatment. If signs and symptoms develop, a number of treatments can help control your multiple myeloma.

CAUSES

It’s not clear what causes myeloma.

Doctors know that myeloma begins with one abnormal plasma cell in your bone marrow — the soft, blood-producing tissue that fills in the center of most of your bones. The abnormal cell multiplies rapidly.

Because cancer cells don’t mature and then die as normal cells do, they accumulate, eventually overwhelming the production of healthy cells. In the bone marrow, myeloma cells crowd out healthy white blood cells and red blood cells, leading to fatigue and an inability to fight infections.

The myeloma cells continue trying to produce antibodies, as healthy plasma cells do, but the myeloma cells produce abnormal antibodies that the body can’t use. Instead, the abnormal antibodies (monoclonal proteins, or M proteins) build up in the body and cause problems, such as damage to the kidneys.

A connection with MGUS

Multiple myeloma almost always starts out as a relatively benign condition called monoclonal gammopathy of undetermined significance (MGUS).

In the United States, about 3 percent of people older than age 50 have MGUS. Each year, about 1 percent of people with MGUS develop multiple myeloma or a related cancer.

MGUS, like multiple myeloma, is marked by the presence of M proteins — produced by abnormal plasma cells — in your blood. However, in MGUS, the levels of M proteins are lower and no damage to the body occurs.

SYMPTOMS

Signs and symptoms of multiple myeloma can vary and, early in the disease, there may be none.

• When signs and symptoms do occur, they can include:
• Bone pain, especially in your spine or chest
• Nausea
• Constipation
• Loss of appetite
• Mental fogginess or confusion
• Fatigue
• Frequent infections
• Weight loss
• Weakness or numbness in your legs
• Excessive thirst

When to see a doctor

Make an appointment with your doctor if you have any persistent signs and symptoms that worry you.