Multiple myeloma is the most common primary bone cancer. It accounts for 1 percent of all cancers. It occurs in about 4 out of every 100,000 people in the United States each year. Multiple myeloma is responsible for the deaths of 10,000 Americans each year.

This disease generally occurs in older adults. Fewer than 3 percent of cases occur in people younger than 40 years of age. Multiple myeloma tends to be more common in men than women. It is twice as common in African Americans as it is in Caucasians.

Multiple myeloma occurs spontaneously. Patients exposed to ionizing radiation and the pesticide dioxin may develop the disease. Infection with some viruses (HIV and human herpes 8) has also been associated with multiple myeloma. No known risk factors are inherited.

Patients usually complain of bone pain. Other symptoms include:

• Fatigue
• Feeling ill
• Fever
• Night sweats

Weight loss is not common in the early stages.

Physically, patients are pale with diffuse bone tenderness, especially around the sternum (breastbone) and pelvis (hips).

Pathologic fractures (fractures caused by tumors) occur frequently. Thirty percent of patients will have their multiple myeloma first discovered when they develop this kind of fracture. The spine is the most common location for a pathological fracture. It can also happen in the ribs and pelvis.

Compression of the spinal cord occurs in 10 percent to 15 percent of patients. This causes pain in the back and legs and numbness and weakness in the legs.

Patients who have high levels of calcium in the blood may experience nausea, fatigue, confusion, constipation, and frequent urination.

Patients with anemia may experience fatigue, weakness, and shortness of breath with exercise.

In advanced cases, patients typically have recurrent infections and can have kidney failure.

Multiple myeloma is named for the "clock face" appearance of cells seen under the microscope. They infiltrate virtually all of a patient's bone marrow. These malignant cells come from changed plasma cells. Plasma cells are white blood cells that secrete antibodies as part of the immune response. The changed plasma cells produce abnormal amounts of an antibody protein. No one knows the exact cause or location of the cellular change.

Multiple myeloma is not confined to a specific bone or location within a bone. It tends to involve the entire skeleton. When only one lesion is found it is called a plasmacytoma. Most doctors believe that plasmacytoma is simply an early, isolated form of multiple myeloma.

Multiple myeloma appears on X-rays as decreased bone density with a lot of "punched out" holes in the bone. These destructive lesions are not surrounded by the white rim of bone seen in other types of destructive lesions. A bone scan may show which bones are involved with multiple myeloma. But, often the lesions cannot be seen. If a bone scan is negative, a skeletal survey is typically performed. This consists of X-rays of many different parts of the skeleton.

The diagnosis is made when a large number of abnormal plasma cells are found in the patient's bone marrow. The doctor obtains this marrow through a bone biopsy.

A blood test can confirm the diagnosis. The patient's blood is checked for abnormal antibodies produced by myeloma cells.

Some forms of multiple myeloma produce proteins that can be detected with a urine analysis.

Patients may also have:

• Anemia (low red blood cell count)
• Leukopenia (low white blood cell count)
• Thrombocytopenia (low platelet count)
• Hypercalcemia (high calcium level in the blood)

Multiple myeloma is currently not curable. Chemotherapy may prolong life expectancy and decrease symptoms.

Research in multiple myeloma has been evolving rapidly. There are currently a number of new biologic agents entering various stages of clinical studies.