MGUS

MGUS stands for monoclonal gammopathy of unknown significance. It is a non-cancerous condition where the body makes an abnormal protein, called a paraprotein.

Although MGUS is not a cancer, people with it have a slightly higher risk of developing:

• myeloma (a cancer of blood cells called plasma cells)
• lymphoma (a cancer of blood cells called lymphocytes).

MGUS affects plasma cells. These are a type of white blood cell made in the bone marrow. Normal plasma cells make proteins called antibodies to help fight infections. With MGUS, some plasma cells make an abnormal type of antibody called a paraprotein (or M protein). For most people, this does not cause any problems.

Each year, about 1 out of 100 people with MGUS (1%) develop a related cancer, such as myeloma or lymphoma. However, most people with MGUS never develop a related cancer and do not need treatment.

Doctors do not know why some people with MGUS develop a cancer and others do not. Your doctor may do regular blood tests to help check for any changes and predict whether the MGUS is likely to change in the future.

MGUS does not usually cause any symptoms. But a small number of people with MGUS have problems with their balance, or numbness or tingling in their hands and feet. This is called peripheral neuropathy. Symptoms may be because of damage to their nerves caused by paraproteins in the blood.

People with nerve problems may be referred to a neurologist. This is a doctor who specialises in conditions of the nervous system.

Some people may also have problems with the kidneys.

MGUS does not usually need treatment as it rarely causes any symptoms. In most people, MGUS remains stable and never causes any problems.

There is a small risk of MGUS developing into a cancer, such as myeloma or lymphoma. If this happens, it is usually a slow-growing lymphoma. This can cause certain symptoms. Always contact your doctor if you have any of these symptoms:

• new or constant bone pain (such as in the back, ribs, hip or pelvis)
• different infections, one after another, that need antibiotics to treat them
• feeling short of breath
• extreme tiredness (fatigue)
• unexplained weight loss
• night sweats
• new lumps or swellings.

Your doctor may also recommend you have regular blood tests. These will be like the ones you had at diagnosis.

In the first year, you may have blood tests every few months. If your blood tests are normal after this time and you have no new symptoms, you have blood tests less often.

If you have new symptoms or blood tests show changes, such as a rising paraprotein level, your doctor may arrange for you to have more frequent tests.

Not everyone with MGUS needs regular follow-up appointments and blood tests. For some people, the chance of it causing problems in their lifetime is so small, no checks are needed. But it is still important to tell your doctor if you get any of the symptoms mentioned above.

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