Multiple myeloma is a cancer of your plasma cells. Plasma cells are a type of white blood cell present in your bone marrow — the soft, blood-producing tissue that fills in the center of most of your bones. The exact cause of multiple myeloma isn't known.

Plasma cells usually make up less than 5 percent of the cells in your bone marrow. But if you have multiple myeloma, a group of abnormal plasma cells (myeloma cells) multiplies, raising the percentage of plasma cells to more than 10 percent of the cells in your bone marrow. The result can be erosion of your bones. The disease also interferes with the function of your bone marrow and immune system, which can lead to anemia and infection. Multiple myeloma may also cause problems with your kidneys.

The disease is called multiple myeloma because myeloma cells can occur in multiple bone marrow sites in your body.

If you have multiple myeloma but aren't experiencing symptoms, your doctors may just need to monitor your condition. If you're experiencing symptoms, a variety of treatments are available.

Although multiple myeloma may not cause symptoms early in the disease, it's likely that you'll experience symptoms as the disease progresses.

Signs and symptoms of the disease can vary from person to person. One of the most common symptoms, however, is bone pain. A common sign is the presence of abnormal proteins — which can be produced by myeloma cells — in your blood or urine. These proteins — which are antibodies or parts of antibodies — are called monoclonal, or M, proteins.

Often discovered during a routine exam, monoclonal proteins may indicate multiple myeloma, but also can indicate other conditions.

Another potential sign of multiple myeloma is a high level of calcium in your blood. This can occur when calcium from affected bones dissolves into your blood. As a result, you may experience signs and symptoms such as:

• Excessive thirst and urination
• Constipation
• Nausea
• Loss of appetite
• Mental confusion

Anemia can occur as myeloma cells replace oxygen-carrying red blood cells in your bone marrow, which may lead to another common symptom — fatigue.

Other signs and symptoms of multiple myeloma may include:

• Bone pain, particularly in your back or ribs
• Unexplained bone fractures
• Repeated infections — such as pneumonia, bladder or kidney infection, or sinusitis
• Weight loss
• Weakness or numbness in your legs

Although the exact cause isn't known, doctors do know that multiple myeloma begins with one abnormal plasma cell in your bone marrow. This abnormal cell then starts to multiply. Because abnormal cells don't mature and then die as normal cells do, they accumulate, eventually overwhelming the production of healthy cells. Healthy bone marrow consists of a small percentage of plasma cells, less than 5 percent. But in people with multiple myeloma, the percentage of plasma cells often increases to more than 10 percent.

Because myeloma cells may circulate in low numbers in your blood, they can populate other bone marrow sites in your body, even far from where they began. Uncontrolled plasma cell growth can damage bones and surrounding tissue. It can also interfere with your immune system's ability to fight infections by inhibiting your body's production of normal antibodies.

Experts aren't sure why this process begins. But, researchers are studying the DNA of plasma cells to try to understand what changes occur that cause these cells to become cancer cells. Though they haven't yet discovered the cause of these changes, they have found some common abnormalities in myeloma cells. For example, many myeloma cells are missing all or part of one chromosome — chromosome 13. Cells with a missing or defective chromosome 13 tend to be more aggressive and harder to treat than cells with a normal chromosome 13.

Multiple myeloma sometimes develops from a harmless condition called monoclonal gammopathy of undetermined significance (MGUS). This condition, like multiple myeloma, is marked by the presence of M proteins — produced by abnormal plasma cells — in your blood. However, in MGUS, the amount of the abnormal proteins isn't high enough to cause harm, and no damage to the bones occurs.

Multiple myeloma isn't contagious. Most people who develop multiple myeloma have no clearly identifiable risk factors for the disease.

Some factors that may increase your risk of multiple myeloma include:

• Age. The majority of people who develop multiple myeloma are older than 50, with the most common age about 70. Few cases occur in people younger than 45.
• Sex. Men are about 50 percent more likely to develop the disease than are women.
• Race. Blacks are about twice as likely to develop multiple myeloma as are whites.
• History of a monoclonal gammopathy of undetermined significance. Every year 1 percent of the people with MGUS in the United States develop multiple myeloma.
• Obesity. Your risk of multiple myeloma is increased if you're overweight or obese.

Other factors that may increase your risk of developing multiple myeloma include exposure to radiation and working in petroleum-related industries.

If you're persistently more tired than you used to be, you've lost weight, and you experience bone pain, repeated infections, loss of appetite, excessive thirst and urination, persistent nausea, increased constipation, or weakness or numbness in your legs, your signs and symptoms may indicate multiple myeloma or other serious diseases. See your doctor to determine the underlying cause.

Your doctor may first detect signs of multiple myeloma before you ever have symptoms — through blood and urine tests conducted during a routine physical exam.

Blood and urine tests
A blood test called serum protein electrophoresis separates your blood proteins and can detect the presence of M proteins in the blood. Parts of M proteins may also be detected in a test of your urine — when found in urine, they're referred to as Bence Jones proteins.

If your doctor discovers M proteins, you'll likely need additional blood tests to measure blood cell counts and levels of calcium, uric acid and creatinine. Your doctor may also conduct other blood tests to check for beta-2-microglobulin — another protein produced by myeloma cells — or to measure the percentage of plasma cells in your bone marrow.

You may also need other tests. They may include:

• Imaging. X-rays of your skeleton can show whether your bones have any thinned-out areas, common in multiple myeloma. If a closer view of your bones is necessary, your doctor may use magnetic resonance imaging (MRI) or computerized tomography (CT) scanning.
• Bone marrow examination. Your doctor may also conduct a bone marrow examination by using a needle to remove a small sample of bone marrow tissue. The sample is then examined under a microscope to check for myeloma cells.

Staging and classification
These tests can help confirm whether you have multiple myeloma or another condition. If tests indicate you have multiple myeloma, the results from these tests allow your doctor to classify the stage of myeloma. Stages range from Stage I (fewer myeloma cells) to Stage III (more myeloma cells) and can be further classified as A (normal kidney function) or B (abnormal kidney function) — as multiple myeloma often causes damage to your kidneys.

Multiple myeloma can result in several complications:

• Impaired immunity. Myeloma cells inhibit the production of antibodies needed for normal immunity. Having multiple myeloma may make you more likely to develop infections, such as pneumonia, sinusitis, bladder or kidney infection, skin infections and shingles.
• Bone problems. Multiple myeloma also can affect your bones, leading to erosion of bone mass and fractures. The condition may cause compression of your spinal cord. Signs of this medical emergency include weakness, or even paralysis, in your legs.
• Impaired kidney function. Multiple myeloma may cause problems with kidney function, including kidney failure. Higher calcium levels in the blood due to eroding bones can interfere with your kidneys' ability to filter your blood's waste. The proteins produced by the myeloma cells can cause similar problems, especially if you become dehydrated.
• Anemia. As cancerous cells crowd out normal blood cells, multiple myeloma can also cause anemia and other blood problems.

Generally, if you have multiple myeloma and aren't experiencing symptoms, you don't need treatment. However, your doctors will likely monitor your condition at variable intervals, checking for signs — such as increasing levels of M protein in your blood or urine — that indicate the disease is progressing. If it is, you may need treatment to help prevent symptoms. The average time between diagnosis and the onset of symptoms is two to three years.

If you're experiencing symptoms, treatment can help relieve pain, control complications of the disease, stabilize your condition and slow the progress of the disease.

Standard treatments
Though there's no cure for multiple myeloma, with good treatment results you can usually return to near-normal activity. The appropriate treatment depends on your needs, medical status and general health. Standard treatment options include:

• Chemotherapy. Chemotherapy is the most common treatment for this disease. It involves using medicines — taken orally as a pill or given through an intravenous (IV) injection — to kill myeloma cells. Chemotherapy is often given in cycles over a period of months, followed by a rest period. Often chemotherapy is discontinued during what is called a plateau phase or remission, during which your M protein level remains stable. You may need chemotherapy again if your M protein level begins to rise.
• Stem cell transplantation. This treatment involves using high-dose chemotherapy along with transfusion of previously collected immature blood cells (stem cells) to replace diseased or damaged marrow. The stem cells can come from you or from a donor, and they may be from either blood or bone marrow.
• Radiation therapy. This treatment uses high-energy penetrating waves to damage myeloma cells and stop their growth. Radiation therapy may be used to target myeloma cells in a specific area — for instance, to more quickly shrink a tumor that's causing pain or destroying a bone.

Other treatments
Other available treatments are being studied to determine their place in treatment of multiple myeloma. Your doctor can discuss with you whether these treatments are appropriate for you. Some of these include:

• Bortezomib (Velcade). Velcade is the newest treatment for resistant forms of multiple myeloma. It's the first drug in a new class of medications called proteasome inhibitors. It works by blocking the action of proteasomes, which causes cancer cells to die. In 2003, the Food and Drug Administration (FDA) approved the drug under an accelerated process as a third-line treatment for multiple myeloma. Because the drug was fast-tracked for approval, it will continue to be studied. However, early findings have been positive. A study from the June 16, 2005, New England Journal of Medicine found that Velcade had more than twice the response rate of a commonly used chemotherapy drug, dexamethasone.
• Thalidomide. Thalidomide, a drug originally used as a sedative and to treat morning sickness in the 1950s, was removed from the market after it was found to cause severe birth defects. The drug, however, received FDA approval again in 1998 as a treatment for skin lesions caused by leprosy. And in May 2006, it was approved, in conjunction with dexamethasone, for the treatment of newly diagnosed cases of multiple myeloma. Thalidomide appears to be an effective treatment for stopping the growth and spread of myeloma cells. Because thalidomide can have serious side effects, such as nerve damage and dizziness, researchers are trying to develop a treatment that acts like thalidomide on myeloma cells without the side effects.
• New therapies. Other new treatments, such as Revlimid, 2-methoxyestradiol, Neovastat and oblimersen, are being tested. Talk to your doctor about what clinical trials may be available to you.

Treating complications
Because multiple myeloma can cause a number of complications, you may also need treatment for those specific conditions. For example:

• Back pain. Taking pain medication or wearing a back brace can help relieve the back pain you might experience with multiple myeloma.
• Kidney complications. People with severe kidney damage may need dialysis.
• Infections. Antibiotics may be necessary to help treat infections or to help reduce your risk of them.
• Bone loss. You may take medications called bisphosphonates, which bind to the surface of your bones and help prevent bone loss.
• Anemia. If you have persistent anemia, your doctor may prescribe erythropoietin injections. Erythropoietin is a naturally occurring hormone made in the kidneys that stimulates the production of red blood cells.

The following tips may help you keep multiple myeloma under control:

• Stay active. Exercise helps keep your bones stronger. If pain keeps you from being active, ask your doctor about ways to lessen the pain.
• Drink fluids. Drinking fluids can help keep you from becoming dehydrated. And by drinking plenty of fluids, you help dilute the Bence Jones protein fragments in your urine, which may help prevent kidney damage.
• Eat a balanced diet. One way to promote your overall health and cope with any form of cancer is to eat well. The amount of M protein in your system isn't affected by how much protein you eat, so there's no need to limit protein intake unless told otherwise by your doctor. Don't take vitamins, herbs or medication without your doctor's approval because they may interfere with your treatment.

A diagnosis of cancer can be extremely challenging. Remember that no matter what your concerns or prognosis, you're not alone. These strategies and resources may make dealing with cancer easier:

• Know what to expect. Find out everything you can about your cancer — the type, stage, risks, your treatment options and their side effects. The more you know, the more active you can be in your care. In addition to talking with your doctor, look for information in your local library and on the Internet. The National Cancer Institute will answer questions over the phone from the public at (800) 4-CANCER, or (800) 422-6237. Or contact the American Cancer Society at (800) ACS-2345, or (800) 227-2345. Information is also available on their Web sites.
• Be proactive. Although you may feel tired and discouraged, don't let others — including your family or your doctor — make important decisions for you. It's vital that you take an active role in your treatment.
• Maintain a strong support system. Having a support system and a positive attitude can help you cope with any issues, pain and anxieties that might occur. Although friends and family can be your best allies, they sometimes may have trouble dealing with your illness. If so, the concern and understanding of a formal support group or others coping with cancer can be especially helpful. Although support groups aren't for everyone, they can be a good source for practical information for you and your family, too. You may also find you develop deep and lasting bonds with people who are going through the same things you are.
• Set reasonable goals. Having goals helps you feel in control and can give you a sense of purpose. But don't choose goals you can't possibly reach. You may not be able work a 40-hour week, for example, but you may be able to work at least part time. In fact, many people find that continuing to work can be helpful.
• Take time for yourself. Eating well, relaxing and getting enough rest can help combat the stress and fatigue of cancer. Also, plan ahead for the downtimes, when you may need to rest more or limit what you do.
• Stay active. Having cancer doesn't mean you have to stop doing the things you enjoy or normally do. For the most part, if you feel well enough to do something, go ahead and do it. It's important to stay involved as much as you can.