Causes
It is not known what causes myeloma. Normally, only 5% or less of the bone marrow is made up of plasma cells. When a plasma cell becomes abnormal and begins multiplying, the cells are then called myeloma cells. Myeloma cells have special "adhesion molecules" that help them target bone marrow. In cases of myeloma, the plasma cells usually make up 10% or more of the bone marrow. Myeloma cells make a special type of protein to stimulate new blood vessels to form. These blood vessels provide oxygen and nutrients to the cancer cells.
Some risk factors for developing multiple myeloma include:
- a family history of multiple myeloma
- being male
- being older than 60 years of age
- people of African descent
- people with monoclonal gammopathy of undetermined significance (MGUS) - a precancerous disease of the plasma cell
There are other possible risk factors, such as obesity or exposure to high dose radiation and chemicals, but these have not been proven.