This information is about myeloma, a type of cancer which affects the plasma cells in your bone marrow (the spongy substance inside some of your bones). We also have a booklet about myeloma which you can download or order for free.

You can also view our information about a related condition called MGUS (monoclonal gammopathy of undetermined significance).

Watch Kaye talk about her myeloma diagnosis and treatment

What is myeloma?

A plasma cell is a type of white blood cell that produces proteins called antibodies, which fight infections in your body. When you have myeloma, your plasma cells produce abnormal antibodies which can't fight infection. On top of this, too many abnormal plasma cells are produced in your bone marrow (the spongy tissue inside some of your bones where your blood cells are made). This means there isn’t enough room for normal red and white blood cells, which both play an important role in keeping you well.

Usually the bone marrow is affected in a number of places around your body, which is why myeloma is sometimes known as ‘multiple myeloma’.

Myeloma is divided into two main groups:

  • Smouldering or asymptomatic myeloma. This is where there are no symptoms or tissue damage.
  • Symptomatic myeloma. This is where there are symptoms and possibly tissue damage.

If you would like to know more about the blood, see our information on bone marrow and how blood cells are made.

Your immune system

Your immune system is a network of cells, tissues and organs which protect your body against infections by finding and killing germs. Antibodies play an important role in your immune system. In myeloma, normal antibodies can be swamped by the production of abnormal antibodies, so your body’s defences will often be low. This means you might get infections that are more severe than usual and last longer.

For more information on reducing your risk of infection, see our fact sheet Understanding infection.

Antibodies, paraproteins and myeloma

Plasma cells normally produce antibodies, which are made of two different kinds of protein: heavy chains and light chains. An antibody is shaped like a 'Y', with two heavy chains and two light chains.

We all have antibodies. When your body is responding to infections, your plasma cells make five main types of antibody (also known as immunoglobulins). These have different heavy chains called G, A, M, D or E. You might hear them called IgG, IgA, IgM, IgD and IgE. The light chains are called either κ (kappa) or λ (lambda).

When you have myeloma, you produce abnormal antibodies instead, called paraproteins. These antibodies can’t fight infections properly. You might hear a paraprotein also being called a monoclonal gammopathy, an M protein or an M-spike. The presence of paraprotein can be an important sign of myeloma, although in some cases, myeloma cells only produce the light chain part of the paraprotein, or more rarely, very little or no paraprotein at all.

Structure of an antibody

Types of myeloma

There are different types of myeloma. Some are very rare, but they are all treated in the same way.

IgG and IgA myeloma

A large majority of people with myeloma will have a type of disease called IgG or IgA myeloma. This means the abnormal plasma cells (myeloma cells) are making too many abnormal IgG or IgA antibodies. The myeloma cells also overwhelm the normal plasma cells, so the level of normal antibodies being produced can also be low.

IgG is the most common type of myeloma. Over half (50%) of cases are this type. Around one in five people with myeloma (20%) will have IgA type.

Free light chain myeloma (formerly known as Bence Jones myeloma)

One in five people with myeloma (20%) have this type. This is where the body produces antibodies that are incomplete, so they may not have a Y-shaped heavy chain, only the light chain (either kappa or lambda). These antibodies are referred to as 'free light chains' because they are not attached to the heavy chains.

A special test known as the serum free light chain assay is done to detect these abnormal light chains. Or, light chains can be measured in the urine – where they’re known as 'Bence Jones protein'.

People with this type of myeloma should receive guidance from their healthcare team about taking extra care of their kidneys, because free light chains can damage them.

Non-secretory myeloma and oligosecretory myeloma

Around three in a hundred people (3%) with symptomatic myeloma get non-secretory myeloma. This is where the abnormal plasma cells do not produce any paraprotein at all. Oligosecretory myeloma is where the plasma cells only produce very small amounts of paraprotein.

What causes myeloma?

Over 5,000 people are diagnosed with myeloma each year in the UK. There are no clear causes, but there are some things which can increase your risk. Here’s what we do know:


The likelihood of developing myeloma rises as you get older, with 95% of cases diagnosed in people aged over 50. It’s very rare for people under 40 to get myeloma. Myeloma doesn’t affect children.


Men are more likely than women to develop myeloma – we don’t know why. In the UK, around six out of ten cases of myeloma (60%) are in men, compared to four out of ten (40%) in women.

Family history

A parent, child, brother or sister of someone with myeloma is two or three times more likely to develop myeloma than other people. However, the risk for any person is still very low.


People of African-Caribbean origin are roughly twice as likely as other races to get myeloma – we don’t know exactly why.


Sometimes, small identical copies (clones) of plasma cells develop and produce a low amount of paraprotein but there are no other features of myeloma. This is called monoclonal gammopathy of undetermined significance (MGUS).

MGUS is quite a common condition which affects about three in a hundred people (3%) over the age of 50 in the UK. It's generally harmless and causes no obvious damage, so no treatment is needed and people aren’t routinely screened for it.

People with MGUS have a higher risk of developing myeloma – around one in a hundred people with MGUS (1%) go on to develop myeloma each year.

Anyone with MGUS will have regular blood and urine tests, to make sure it’s not progressing.

For more information on MGUS, read our fact sheet.

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