What is multiple myeloma?
Multiple myeloma (also called Kahler disease, bone marrow cancer or plasma cell myeloma) is a type of cancer that begins in the blood's plasma cells. Made in the bone marrow (the soft, inner part of some bones), plasma cells are a type of white blood cell (B lymphocyte) that produces antibodies (e.g., monoclonal proteins or M-proteins) which fight infection.
A cancer of the bone marrow, multiple myeloma causes an excess of abnormal plasma cells (myeloma cells), which form tumors in multiple locations throughout the bone marrow. These tumors begin to overcrowd the bone marrow and prevent normal reproduction of healthy blood cells.
Although it only accounts for about 1 percent of overall cancers, multiple myeloma is the second most prevalent blood cancer after non-Hodgkin lymphoma. The American Cancer Society estimates 30,280 Americans will be diagnosed with this disease in 2017.
Sometimes called bone marrow cancer because it develops in plasma cells in bone marrow, multiple myeloma is more common in African Americans than white Americans, and incidence rises with age. The average age at diagnosis is 69, according to the National Cancer Institute, while people under 45 rarely develop the disease.
How multiple myeloma develops
There are many kinds of cells that make up our blood, including red blood cells (RBCs), white blood cells (WBCs) and platelets. A particular category of WBCs, called lymphocytes, are a vital part of our immune defense.
There are two main types of lymphocytes, B lymphocytes (B cells) and T lymphocytes (T cells), both of which originate in the bone marrow. As the B cells mature, some develop into plasma cells. Plasma cells help the body’s immune system fight disease by producing antibody proteins in response to bacterial infections or viruses.
When malignant plasma cells (or myeloma cells) collect in only one bone and form a single mass or tumor, it is called a plasmacytoma. In most cases, however, the myeloma cells grow out of control and collect in many bones, often forming many tumors. When this happens, the disease is called multiple myeloma.