What is myeloma?
Myeloma is a type of cancer that affects cells called plasma cells. Plasma cells are found in bone marrow alongside maturing blood cells. The job of plasma cells is to make immunoglobulins (Ig) which are chain-like proteins that attach to bacteria and viruses to protect the body from infection– so-called antibodies. There are 5 different types of antibodies and these are named IgA, IgG, IgE, IgM and IgD. Each antibody or immunoglobulin is made up of heavy chains and light chains. Levels of immunoglobulins can be measured in the blood. The presence of high levels of immunoglobulin or components of immunoglobulin in the blood is abnormal. This may be described in the medical evidence as ‘paraproteinaemia’ or myeloma protein (M protein). Protein in blood can be separated out and examined using a test called ‘electrophoresis’, normally this shows that there are many different types of immunoglobulin, but in myeloma there are more immunoglobulins than normal and most of these are identical to each other. This immunoglobulin is produced by multiple identical plasma cells. A set of identical cells is called a clone. As these proteins are produced by one clone the protein is called monoclonal [mono=one]. Sometimes in myeloma the abnormal plasma cells don’t finish the job of making up the chains into immunoglobulin proteins and free light chains or heavy chains may be found in the blood rather than complete immunoglobulins. This type of disease may be called ‘light chain myeloma’ or ‘Bence Jones only Myeloma’ in the medical evidence. Treatment of this condition is as for myeloma as described in this guidance. Rarely it may be difficult to detect the excess immunoglobulins in the blood and this is called ‘Non-Secretory Myeloma’. Again treatment follows this myeloma guidance.
There is a spectrum of abnormalities of plasma cells, which are variants of myeloma. These variants are described below. Outcome may be very different between types so it is important to decide which one a person has when using the guidance. The variants covered by this guidance are:
- Multiple Myeloma – the main focus of this guidance – a disease caused by the effects of plasma cells through out the body producing excess immunoglobulins – a diffuse sort of cancer. 94% of people with plasma cell disorders have this type. Rarely it may be difficult to detect the excess immunoglobulins in the blood and this is called ‘Non-Secretory Myeloma’
- Isolated Plasmacytoma of Bone – abnormal plasma cells producing immunoglobulins in one bone only – a localised sort of cancer of bone. 3% of people have this type.
- Solitary Extramedullary Plasmacytoma - abnormal plasma cells producing immunoglobulins in one soft tissue area of the body – usually in the head or neck – a localised sort of soft tissue cancer. 3% have this type of myeloma.
- Monoclonal Gammopathy of Undetermined Significance (MGUS) – Slightly abnormal levels of immunoglobulins have been found in the blood, there are no symptoms of disease and no treatment is required. 1-2% of people with this will go on to develop multiple myeloma each year. People with MGUS do not have myeloma but might develop it in the future.
Symptoms of myeloma are caused by the presence of excess plasma cells in the bone marrow. These excess cells crowd out normal bone marrow cells and may cause erosion of bones and raised calcium in the blood secondary to bone erosion. Damage to organs may be caused by the abnormal proteins circulating in the blood.
Prevalence
Myeloma affects 3700 people each year in the UK and about 2600 people die of it. It is very rare in the under 40s and more common in very elderly people. People (of working age) with myeloma are more likely to have intensive treatment including peripheral blood stem cell transplant (PBSCT) than older people; 5 year survival in this group is about 40%. 10 year survival is about 20%. Before chemotherapy treatment median survival from diagnosis was about 7 months. There is no screening programme for myeloma.
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Amended February 2009
