Changing pattern of presentation in monoclonal gammopathy of undetermined significance: a single-center experience with 1400 patients.

To assess whether the pattern of presentation and the outcome of monoclonal gammopathy of undetermined significance (MGUS) have changed over the last 3 decades, we evaluated 1400 patients, divided into 3 groups: group I (1975-1987), group II (1988-1997), and group III (1998-2007). We observed a significant increase in age (p = 0.001), IgM and biclonal MGUS (p = 0.003), hemoglobin (p < 0.0001), and albumin (p = 0.0001), and a significant reduction of monoclonal (M)-protein concentration (p < 0.0001), percentage of bone marrow plasma cells (p < 0.0001), and beta2-microglobulin (p = 0.0001) over the 3 decades. The proportion of patients with M-protein <1.5 g/dL was significantly higher in group III (66%) than in group II (44%) and group I (26%) (p < 0.0001). By Kaplan-Meier analysis, group III had a significantly lower 5-year probability of transformation (5%) compared to group II (12%) and group I (22%) (p = 0.003). Patients with M-protein <1.5 g/dL had the same life expectancy as the general population (standardized mortality ratio 1.09; p = 0.41). In conclusion, we found that the pattern of presentation of MGUS has changed over time and now includes a higher proportion of patients with more favorable presenting features and probably a better outcome compared to patients presenting in the past. This changing scenario calls for revising the current concepts of the clinical significance of MGUS and the management of patients.