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Abstract
Monoclon
al gammopathy of undetermined significance of the immunoglobulin M class was diagnosed in 213 patients at the Mayo Clinic, 29 (14 % ) of whom developed lymphoma, W
aldenstr?m macroglobulinemia, or a related disorder over 1567 person-years of follow-up. The cumulative probability of progression was 10 % at 5 years, 18 % at 10 years, and 24 % at 15 years, or approximately 1.5 % per year. The concentration of serum monoclon
al protein at diagnosis and the initi
al serum
albumin v
alue were the only independent predictors of progression with multivariate an
alysis.
By contrast, during 285 person-years of follow-up, 34 (71 % ) of 48 patients with smoldering Waldenstr?m macroglobulinemia (SWM) progressed to Waldenstr?m macroglobulinemia (WM), which required therapy, along with amyloid light chain (AL) amyloidosis (1) and lymphoma (1). The cumulative probability of progression was 6 % at 1 year, 39 % at 3 years, 59 % at 5 years, and 65 % at 10 years. The percentage of lymphoplasmacytic cells in the bone marrow, size of the serum monoclonal (M) spike, and hemoglobin value were significant independent risk factors for progression.