Myeloma

What is myeloma?

Myeloma is a type of blood cancer. It develops from cells in the bone marrow called plasma cells. As bone marrow is found throughout the body, myeloma can affect multiple areas at the same time, and the disease is often called multiple myeloma.

Learn more about:

• The blood
• How myeloma starts
• How myeloma affects the body
• How is it different from leukaemia?
• Who gets myeloma?
• What causes myeloma?

The blood

Blood is pumped around your body to provide oxygen and nutrients to your tissues, and to remove waste products. It is made up of red blood cells, white blood cells and platelets, and each has a set function.

All three types of blood cells live for a limited time and need to be continually replaced. Most are made in the bone marrow, which is the spongy part in the centre of the bones.

The bone marrow contains stem cells. These are unspecialised blood cells that develop into mature red or white blood cells or platelets. Once mature, the blood cells are usually released into the bloodstream to carry out their set functions.

How myeloma starts

Bone marrow produces three main types of blood cells: red cells, white cells and platelets. Plasma cells are a special type of white blood cell. Myeloma starts when the plasma cells become abnormal and multiply, crowding the bone marrow. They usually also release an abnormal antibody (paraprotein) into the blood.

How myeloma affects the body

Myeloma begins when abnormal plasma cells, known as myeloma cells, start multiplying. Normal plasma cells make a wide variety of antibodies that help the body fight infections, but myeloma cells make an abnormal antibody known as paraprotein, M-protein or monoclonal protein. Paraprotein is found in the blood of most people who have myeloma.

Because the myeloma cells crowd out the bone marrow, there is less space for normal blood cells to develop and keep you healthy. A lack of:

• normal plasma cells and other white blood cells can make a person more likely to get infections
• red blood cells (anaemia) can cause fatigue
• platelets (thrombocytopenia) can cause bleeding and bruising.

How is it different from leukaemia?

Myeloma and leukaemia are both types of blood cancer, but they affect the body differently. Leukaemia is a cancer of the white blood cells and is easily detected on a blood test. Myeloma is a cancer of the plasma cells, which are not usually found in the blood. Plasma cells normally stay in the bone marrow.

Who gets myeloma?

Myeloma is not a common disease. About 1750 people in Australia are diagnosed with the disease each year. It accounts for 15% of blood cancers and 1% of all cancers generally. The disease is more often found in people over 60, which is partly explained by the ageing population. It is rare in people under 40. Myeloma is slightly more common in men than in women.

What causes myeloma?

The causes of myeloma are unknown. We know that plasma cells become cancerous when there are certain changes in their DNA. DNA is found in all cells. It carries instructions that control how cells work. However, we do not yet know what causes DNA to change.

Exposure to certain chemicals (e.g. dioxins used in industry), high levels of radiation (e.g. from working in a nuclear power plant) and viruses (such as HIV) have been linked to an increased risk of myeloma, but they have not been proven to cause it.

People with monoclonal gammopathy of undetermined significance (MGUS) are more likely to develop myeloma.

Myeloma is not considered to be hereditary (inherited) and there is little risk of passing it on to your children. It is rare for more than one person in a family to be affected by myeloma, although this does happen occasionally.