MGUS (monoclonal gammopathy of unknown significance) is a non-cancerous condition where the body makes an abnormal protein, called a paraprotein.
MGUS is not a cancer, but 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, a type of white blood cell that is 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). This paraprotein does not do anything useful, and for most people it does not cause any problems.
Each year, about 1 out of 100 people with MGUS (1%) develop a related cancer. So most people with MGUS never develop a cancer because of it, or need any 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 in the MGUS and predict whether it is likely to change in the future.