Multiple myeloma is the most common primary bone cancer. It accounts for 1% of all cancers. It occurs in about 20,000 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% 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.
Multiply myeloma 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 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:
- Feeling ill
- 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% to 15% 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.
Several tests are used to confirm a diagnosis of multiple myeloma, including x-rays, bone scans, a bone biopsy, and a blood test.
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.
The standard treatment medications are melphalan and prednisone.
The median survival rate is three years with this treatment alone. For patients in whom this therapy is ineffective, alternatives include:
- VBMCP (vincristine, carmustine, melphalan, cyclophosphamide and prednisone)
- VAD (vincristine, adriamycin and dexamethasone)
These treatments may cause severe muscle weakness. They may also increase the chance of infections.
Thalidomide and interferon are also sometimes used.
Fortunately, a recent advancement in the treatment of multiple myeloma has increased response rates and survival. This treatment consists of high-dose chemotherapy, followed by autologous stem cell transplantation. With this treatment, patients have a 20% chance of living longer than 10 years. This stem cell transplantation involves:
- Harvesting a patient's own blood cells
- Conditioning them with very high doses of melphalan
- Re-infusing the blood cells back into the patient
Radiation therapy is reserved for decreasing the size of symptomatic bone lesions.
Supportive care is critical. This includes comfort measures, pain control, and interventions that maintain function. Supportive care includes managing the bone disease, anemia, infections, kidney failure, and pain associated with multiple myeloma.
- Bisphosphonates (medication) can prevent destructive bone lesions and spine fractures.
- Erythropoetin or occasional blood transfusions can manage anemia.
- Antibody infusions and vaccinations can help patients with recurrent infections.
- Corticosteroids and hydration can be used to treat high blood calcium concentrations (from bone loss) and dehydration.
- Narcotics can address the pain associated with bone lesions.
Surgery will not cure multiple myeloma. Surgery is used to treat fractures and impending fractures in the spine, pelvis, hip, and shoulder. The goal of these surgeries is to decrease pain and maintain function.
Internal fixation augmented with cement is frequently recommended, as are joint replacements and vertebroplasties (for spine fractures). Surgery does not alter the survival rate, but it does increase the quality of life.
Research in multiple myeloma has been evolving rapidly. There are currently a number of new biologic agents entering various stages of clinical studies.
The American Academy of Orthopaedic Surgeons
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