Multiple myeloma is cancer that starts in the plasma cells in bone marrow. Bone marrow is the soft, spongy tissue found inside most bones. It helps make blood cells.

Plasma cells help your body fight infection by producing proteins called antibodies. With multiple myeloma, plasma cells grow out of control in the bone marrow and form tumors in the areas of solid bone. The growth of these bone tumors weakens the solid bones and also makes it harder for the bone marrow to make healthy blood cells and platelets

Plasma cell dyscrasia; Plasma cell myeloma; Malignant plasmacytoma; Plasmacytoma of bone; Myeloma - multiple

The exact cause of multiple myeloma is not clear. Past treatment with radiation therapy raises the risk of this type of cancer. Multiple myeloma mainly affects older adults.

Multiple myeloma most commonly causes a low red blood cell count (anemia), which can lead to fatigue and shortness of breath. It can also cause low white blood cell count, which makes you more likely to get infections. Multiple myeloma also causes low platelet count, which can lead to abnormal bleeding.

As the cancer cells grow in the bone marrow, you may have bone or back pain most often in the ribs or back.

If cancer grows in the spine bones, pressure on the nerves may result. This can lead to numbness or weakness of the arms or legs.

Blood tests can help diagnose this disease. These tests include:

• Albumin level
• Calcium level
• Total protein level
• Kidney function blood tests
• Complete blood count (CBC)
• Blood and urine tests to check to identify proteins, or antibodies (immunofixation)
• Blood tests to quickly and accurately measure the specific level of certain proteins called immunoglobulins (nephelometry)

This list is not all-inclusive.

Bone x-rays may show fractures or hollowed out areas of bone. If your doctor suspects this type of cancer, a bone marrow biopsy will be performed.

Bone density testing may show bone loss.

People who have mild disease or in whom the diagnosis is not certain are often not treated. Instead they are closely watched. Some people have a slow-developing form of multiple myeloma (smoldering myeloma) that takes years to cause symptoms.

Chemotherapy is usually used to treat multiple myeloma. It is most often given to prevent complications of multiple myeloma such as bone fractures and kidney damage.

Radiation therapy may be done to relieve bone pain or treat a bone tumor.

Two types of bone marrow transplants may be tried:

• Autologous bone marrow or stem cell transplantation is done using the person's own stem cells.
• Allogeneic transplant uses of someone else’s stem cells. This treatment has serious risks but may offer the chance of long-term cure.

You can ease the stress of illness by joining a cancer support group. Sharing with others who have common experiences and problems can help you not feel alone.

Survival of multiple myeloma depends on the patient's age and the stage of disease. In some cases, the disease progresses very rapidly. In other cases, it takes years to worsen.

Chemotherapy and transplants rarely lead to a permanent cure.

Kidney failure is a frequent complication. Others may include:

• Bone fractures
• High levels of calcium in the blood, which can be very dangerous
• Increased chances for infection, especially in the lungs
• Weakness or loss of movement due to tumor pressing on spinal cord 

Call your doctor if you have multiple myeloma and you develop an infection, or numbness, loss of movement, or loss of sensation.

National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Multiple Myeloma. Version 1.2013. Available at http://www.nccn.org/professionals/physician_gls/pdf/myeloma.pdf. Accessed 01/10/2013.

Rajkumar SV, Dispenzieri A. Multiple myeloma and related disorders. In: Abeloff MD, Armitage JO, Niederhuber JE, et al., eds. Abeloff’s Clinical Oncology. 4th ed. Philadelphia, PA: Elsevier Churchill-Livingstone; 2008:chap 110.

Rajkumar SV. Plasma cell disorders. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011: chap 193.