What is myeloma?
Myeloma is a relatively rare cancer — accounting for around 10 percent of blood cancer cases. It develops in plasma cells, white blood cells that grow in bone marrow. Myeloma most often affects the aged — most cases are diagnosed in people age 65 and older. Although myeloma grows within bone, it is not considered bone cancer.
This year more than 30,000 people in the United States will be diagnosed with myeloma, according to the American Cancer Society.
Parts of the body involved in myeloma include:
- Bone marrow, spongy blood-producing tissue inside the bones, where all of the blood in the body is produced and where malignant (abnormal) plasma cells grow.
- Plasma cells, produced in the bone marrow and a part of the immune system, are a type of white blood cell that plays an important role in creating antibodies that fight infection. In myeloma plasma cells are abnormal.
- Immunoglobulins, another word for antibodies — proteins produced by plasma cells that are a crucial part of the immune response. They bind to infectious agents, like bacteria or viruses, which identifies them for destruction by other immune system cells.
- Bone cells, specifically osteoblasts that make bone and osteoclasts that dissolve bone. Myeloma cells produce a substance that stimulates breakdown of bone by osteoclasts — and inhibits the activity of osteoblasts — producing holes in the bone called “lytic lesions.”
- The nervous system may also be involved with myeloma. Nerve damage may be caused by toxic, abnormal proteins produced by myeloma cells.