This is a cancer of the plasma cells in bone marrow. Plasma cells are a type of white blood cell that makes antibodies.
Myeloma cells spread through the bone marrow. They can damage your bones and crowd out healthy blood cells. These cells also make antibodies that can't fight off infections.
This cancer is often called multiple myeloma because it's found in many parts of your bone marrow.
Men over age 50 are most likely to get it.