Factors predicting evolution to symptomatic disease were investigated in 27 patients with smouldering Waldenstrom's macroglobulinemia (SWM) among 172 patients with Waldenstom's macroglobulinemia (WM), selected on the basis of the following criteria: (1) IgM paraprotein > 3 g/dL, and/or (2) bone marrow (BM) lymphoplasmacytoid (LPC) infiltration >or= 30%, and/or (3) diffuse infiltration pattern on BM biopsy, and (4) no treatment requirement for at least 12 months. Cumulative probability of survival was calculated by means of Kaplan-Meier. The Mantel and Haenszel test and multivariate Cox model were used to identify possible predictors for evolution. At a median follow-up of 79 months (range, 14 to 204), 11 patients (40.7%) showed progression to symptomatic disease, with the median interval from diagnosis being 46 months (range, 12 to 154). Event-free survival (EFS) at 5 and 10 years was 65% (95% confidence interval [CI], 45% to 85%) and 53% (95% CI, 31% to 75%), respectively. At multivariate analysis, paraprotein > 3 g/dL (hazard ratio [HR], 15.1; 95% CI, 3.01 to 75.64; P <.0009) and hemoglobin <or= 12.5 g/dL (HR, 3.75; 95% CI, 1.05 to 13.34; P <.042) independently predicted transformation into symptomatic disease (P <.0006). Neither BM findings nor other laboratory parameter was associated with overt WM development. In conclusion, in SWM monoclonal IgM levels > 3 g/dL and hemoglobin levels <or= 12.5 gr/dL are likely to predict SWM transformation into active disease requiring treatment.
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