More about the disease
Incidence
Men are about one and a half times more likely than women to develop myeloma, which never affects children and mainly affects older people. African - Caribbean people are about twice as likely as white or Asian people to develop myeloma.
About 1 in 200 people will develop it at some point in their life. The most common age for myeloma to be diagnosed is about 72 years. The condition is very rare in people under 40 years, and about 80% of all patients are aged over 65 when they are diagnosed.
A parent, child, brother or sister of a patient has about a two or three times higher chance than others of developing myeloma or MGUS (see below). The risk for any individual, however, is still very low.
There are nearly 5,000 people diagnosed with myeloma each year in the UK.
Causes
In almost all cases of myeloma there is no known cause. Certain things are known to be associated with a higher chance of developing myeloma. These are called risk factors. Risk factors for myeloma include a condition called MGUS, age, gender, family history and ethnicity.
- A healthy person’s blood contains a mixture of many different antibodies. In some diseases very large amounts of identical antibody are produced; in these cases the antibodies produced are of no use to help fight infection. This is known as a monoclonal gammopathy (gamma globulin is another name for antibody molecules). When a person is found to have a monoclonal gammopathy with no clear cause, this is called MGUS. MGUS is the single most important risk factor for myeloma; each year about 1 in 100 people with MGUS develop myeloma. It is not a cause of myeloma; most experts consider MGUS to be a very early stage of myeloma but one which, in most cases, does not develop any further. Anyone who is found to have MGUS will have regular follow-ups to check if it is progressing.
- Myeloma does not affect children and it becomes more common with increasing age. It is very rare under the age of 40 years and most affected people are aged over 65.
- Myeloma is about twice as common in African-Caribbean people as in white people. This suggests that there might be genes which affect the chance of developing myeloma.
- Myeloma is slightly more common in men than in women, about 130 men are diagnosed for every 100 women.
- Close relatives of people with myeloma or MGUS are two to three times more likely to develop myeloma than people with no affected family members. This might be because of shared genes or because close relatives often live together and might be exposed to something in their surroundings which increases the risk. It is important to remember that, because the risk of myeloma is very low, this increased risk is still very small. Most people with myeloma do not have any affected family members.
You can find out more about causes of myeloma here: beatingbloodcancers.org.uk/myelomalinks
Staging
Staging describes the extent or severity of a person’s cancer. Staging for solid cancers, like breast or lung cancer is based on the size of the original tumour and on how much it spreads from the original site of the tumour. For conditions like myeloma, this system is not helpful because the myeloma cells are spread throughout the bone marrow.
Myeloma staging is based on two laboratory results. These are the amounts of two proteins, called albumin and β2-microglobulin (β2M) in your blood. Albumin is normally the most common protein in the blood, but in myeloma the amount of albumin is reduced. β2M is a protein found on the surface of all lymphocytes; because the abnormal cells in myeloma are lymphocytes, the level of β2M gives an indication of the number of myeloma cells in your body.
Myeloma is staged on the basis of the levels of two factors in the blood; albumin and β2M. More advanced disease is indicated by
lower levels of albumin or by higher levels of β2M. This is called the international staging system (ISS) and recognises three stages:
- Stage I Both albumin and β2M levels are normal or near normal
- Stage II Either albumin is low with normal β2M, or β2M is moderately raised
- Stage III β2M levels are much higher than normal
You can find out more about staging of myeloma here: beatingbloodcancers.org.uk/myelomalinks
Related conditions
There are several conditions which are closely related to myeloma but which differ from it either in the results of laboratory tests
or in the way in which they affect you. If you are affected by one of these conditions, your consultant will explain what this means for you.
MGUS
Most, probably all, people who develop myeloma have previously had a condition called monoclonal gammopathy of undetermined significance (MGUS). MGUS means that a patient has a raised level of paraprotein (also called M-protein) but no symptoms of myeloma or damage to organs. MGUS can only be diagnosed if you have a special test which detects paraprotein in your blood or urine. It is not routine practice to screen healthy people for MGUS or for myeloma.
Plasmacytoma
Plasmacytoma is a condition similar to myeloma but with the plasma cells found in one place in your body – usually in bone. Sometimes in plasmacytoma the plasma cells are not in the bones but in other parts of the body – this is called soft tissue plasmacytoma.
Plasma cell leukaemia
Plasma cell leukaemia may be a late stage of myeloma, with plasma cells present in the blood or it may occur as a separate condition with no bone damage or damage to other tissues.
Waldenstrom macroglobulinaemia
A condition called Waldenstrom macroglobulinaemia (WM) is associated with raised levels of paraprotein. This has in the past been
regarded as a form of myeloma, but is now usually regarded as a rare type of non-Hodgkin lymphoma.
Amyloidosis
A condition called amyloidosis may affect people with myeloma; amyloid is an abnormal protein made up of light chains. Amyloidosis can also occur as an inherited condition and in association with other blood disorders.
You can find out more about conditions related to myeloma here: beatingbloodcancers.org.uk/myelomalinks