Myeloma is a cancer of plasma cells in the bone marrow.
What myeloma is
Myeloma is a type of cancer that develops from cells in the bone marrow called plasma cells. Bone marrow is the spongy tissue found inside the inner part of some of our large bones. The bone marrow produces different types of blood cells.
Myeloma can develop wherever there are plasma cells. So it can be anywhere there is bone marrow, including the pelvis, spine and ribcage. As it can occur in several places in the body, it is often called multiple myeloma.
Plasma cells and immunity
Plasma cells are part of the immune system. They make proteins called antibodies. These are large protein molecules also called immunoglobulins. The plasma cells make antibodies when the body responds to infections. They make different antibodies for different infections. Antibodies attack and help to kill bacteria and viruses.
There are 5 main types of antibody (immunoglobulin) – A, G, M, D and E. In each patient, the myeloma cells produce an abnormal form of one of these types of antibody. You might hear your doctor call the antibodies proteins, paraproteins, or a monoclonal spike.
In most people with myeloma the abnormal antibody can be found in the blood. In some the abnormal antibody is found in the urine. The abnormal antibody does not work properly and isn't able to fight infections.
Blood cells and myeloma
To understand why myeloma affects you the way it does, it helps to understand how blood cells are normally produced and what they do.
Usually bone marrow makes blood cells in a controlled way, when your body needs them. All blood cells start as the same type of cell, called a stem cell. As they develop (mature), they turn into one of three types of blood cell:
- white blood cells (leucocytes)
- red blood cells (erythrocytes)
- platelets (thrombocytes)
Plasma cells develop from a type of white blood cell called B lymphocytes. In myeloma, too many plasma cells are made and they are all of the same type. They crowd the bone marrow. This means that there is not enough space for making normal white cells, red cells and platelets.
What your blood cells do
The white cells are important for fighting infection. If you don't have enough white blood cells, you will pick up more infections, and infections might take longer to get better.
Red blood cells carry oxygen round the body. If you haven't got enough red blood cells, you have anaemia. This can make you tired and breathless.
Platelets are important for normal blood clotting. If you don't have enough platelets, you might bleed more. You might have nosebleeds, very heavy periods, or a fine rash of red spots caused by bleeding into the skin.