MGUS Is a Precursor to Multiple Myeloma  

This week's "Ask Dr. Durie" comes from a patient wanting to know what MGUS is. This is obviously a very important question since we use this terminology quite a bit. MGUS stands for monoclonal gammopathy of undetermined significance. What this means is that a monoclonal protein, which is characteristic of myeloma, has been discovered in the blood of a patient. 

Now, in the case of MGUS, the level of the protein is rather low, and there are no findings that indicate active myeloma. This is an alert to the possibility that myeloma could emerge in the future, but the level of myeloma-type protein is not high enough to indicate active myeloma. Therefore, MGUS is called a precursor condition that can turn into myeloma. Unfortunately, the rate of turning into myeloma is rather low, occurring only in 1% of patients every year. That means that 99% of patients will still continue to have MGUS, which obviously needs to be monitored. 

We know that everyone who develops myeloma has actually had MGUS in the past. However, since only a small percentage of MGUS turns into myeloma, not all MGUS actually turns into myeloma. So the bottom line here is that MGUS is a very important precursor or condition that we need to be alert to. It needs to be monitored. A very large study ongoing in Iceland called iStopMM is screening for MGUS with the idea of identifying it early and assessing if patients might be in the category where progression to myeloma might occur. This would allow the possibility of early intervention to prevent that progression to active disease. 

Although MGUS is a stable precursor condition, it's a very active area for research. By studying MGUS and its tendency to progress or not, we can have a big impact on the ultimate outcome of individuals with this type of monoclonal gammopathy.