A Long-Term Study of Prognosis in Monoclonal Gammopathy of Undetermined Significance

A monoclonal gammopathy of undetermined significance (MGUS) is diagnosed when there is serum monoclonal protein at a concentration of 3 g per deciliter or less in the absence of evidence of multiple myeloma or a related disorder. The condition is not rare in people over the age of 50 years and may progress to full-blown multiple myeloma over a period of years. This study of almost 1400 patients, who were followed for up to 35 years, defines the risk of progression to multiple myeloma and the important predictors of progression. Monoclonal gammopathy of undetermined significance (MGUS) affects up to 2 percent of persons 50 years of age or older and about 3 percent of those older than 70 years. 1 – 5 It is defined by the presence of serum monoclonal protein at a concentration of 3 g per deciliter or less; no monoclonal protein or only moderate amounts of monoclonal light chains in the urine; the absence of lytic bone lesions, anemia, hypercalcemia, and renal insufficiency related to the monoclonal protein 6 , 7 ; and (if this determination is made) a proportion of plasma cells in the bone marrow of 10 percent . . .