What is multiple myeloma?

Multiple myeloma is a cancer that starts in plasma cells, which are made in the bone marrow. Bone marrow is the soft, spongy material that fills the centre of most bones (those where blood cells are made). Plasma cells are a type of white blood cell. Their job is to make antibodies that help fight infections.

Myeloma begins when a plasma cell becomes abnormal and begins to divide uncontrollably, making more and more abnormal plasma cells. Abnormal plasma cells are called myeloma cells. Eventually, the growing number of myeloma cells:

crowd out the normal blood cells in the bone marrow and prevent them from working properly
can spread to the solid part of the bone and cause pain or fractures
upset the balance of certain body minerals, such as calcium, and prevent other organs, such as the kidneys and nerves, from working properly

The disease is called multiple myeloma because it affects many bones. If myeloma cells form a tumour in only one bone, it’s called a plasmacytoma. For information on multiple myloma or plasmacytoma and other plasma cell cancers, please e-mail us or call our Cancer Information Service at 1 888 939-3333.

Last modified on: 09 December 2009