MALIGNANT TRANSFORMATION AND LIFE EXPECTANCY IN MONOCLONAL GAMMOPATHY OF UNDETERMINED SIGNIFICANCE

The actuarial probability of malignant transformation and the impact on expected survival were analysed in a series of 128 persons diagnosed with monoclonal gammopathy of undetermined significance (MGUS) over a 20-year period. At a median follow-up of 56 months the M-component remains stable in 101 patients (78.9%), 14 patients (10.9%) have died from non-related disorders and 13 (10.2%) have developed malignant transformation of MGUS (multiple myeloma, 10, primary amyloidosis, two, Waldenstrom's macroglobulinaemia, one). The actuarial probability of malignant transformation at 5 and 10 years was 8.5% and 19.2%, respectively. When different presenting features were analysed for predictive value of the malignant transformation, the IgA type of MGUS was the only variable associated with a higher probability of such an event (P<0.025). Although no significant difference was observed between the survival probability of persons with MGUS and that of the control population, the development of malignant transformation was associated with a shorter survival (P<0.001).