Multiple Myeloma

Multiple myeloma, a cancer of the plasma cell, is an incurable but treatable disease. Multiple myeloma (also known as myeloma or plasma cell myeloma) is a progressive hematologic (blood) disease. It is a cancer of the plasma cell, an important part of the immune system that produces immunoglobulins (antibodies) to help fight infection and disease. Multiple myeloma is characterized by excessive numbers of abnormal plasma cells in the bone marrow and overproduction of intact monoclonal immunoglobulin.
Hypercalcemia, anemia, renal damage, increased susceptibility to bacterial infection, and impaired production of normal immunoglobulin are common clinical manifestations of multiple myeloma. It is often also characterized by diffuse osteoporosis, usually in the pelvis, spine, ribs, and skull.
It is normal for plasma cells to develop from B cells in lymph nodes as an immune response to disease or infection. Transformation of a normal B cell into a malignant plasma cell involves a multi-step process that includes multiple genetic abnormalities. Finally, the resulting plasma cells become malignant, meaning they continue to divide unchecked, generating more malignant plasma cells. These myeloma cells travel through the bloodstream and collect in the bone marrow, where they cause permanent damage to healthy tissue. We have recently learned that the interaction between the plasma cells and the bone marrow microenvironment is as important as the genetic changes in the development of these malignant cells.
As tumors grow, they invade the hard outer part of the bone, the solid tissue. In most cases, the myeloma cells spread into the cavities of all the large bones of the body, forming multiple small lesions. This is why the disease is known as "multiple" myeloma. In some cases, collections of plasma cells arise either within bone or in soft tissues as masses or tumors.
Multiple myeloma is the second most prevalent blood cancer after non-Hodgkin's lymphoma. It represents approximately 1% of all cancers and 2% of all cancer deaths. Recent statistics indicate both increasing incidence and earlier age of onset. The average age at diagnosis is about 68 years, and only 1% of cases are diagnosed in individuals under the age of 40. Approximately 50,000 Americans currently have myeloma, and the American Cancer Society estimates that approximately 15,980 new cases of myeloma were diagnosed during 2005. A recent study found the incidence of myeloma to be 4.1 cases per 100,000 Caucasian Americans.
Although a tremendous amount of work has gone into the search for the cause of multiple myeloma, to date no cause for this disease has been identified. However, the search for a cause has suggested possible associations between myeloma and a decline in the immune system, genetic factors, certain occupations, certain viruses, exposure to certain chemicals including Agent Orange, and exposure to radiation.
It is important to remember that in most cases, individuals who develop multiple myeloma have no clear risk factors. Myeloma may be the result of several factors acting together.
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