Epidemiology of Monoclonal Gammopathy of Undetermined Significance (MGUS): The experience from the specialized registry of hematologic malignancies of Basse-Normandie (France).

Multiple myeloma (MM) is the third most common haematologic malignancy in European countries, and is usually preceded by Monoclonal Gammopathy of Undetermined Significance (MGUS). Therefore epidemiologic studies of MGUS are very limited in a population-based status. Here we report all new cases of MGUS exhaustively recorded by the Basse-Normandie Regional Registry for Hematologic Malignancies (a French region registry) between January 1997 and December 2005, and analyze outcome of patients until 2009 in term of evolution in MM or death. All cases were analyzed by an expert file review, and MGUS diagnosis was retained for: evidence of a monoclonal component <30 g/l and no CRAB criteria (hyperCalcemia, renal insufficiency, anemia, bone lesions). We showed that the world standardized incidence rate (WSR) for MGUS was 3.76 ± 0.26 per 100,000 inhabitants, increasing regularly with age, and that the median overall survival (OS) was 115.9 months (CI 95%: 10.5-130.2 months) with 78.3% patients alive at 5 years (CI 95%: 74.1-81.9%). We also observed a rate of progression to multiple myeloma of 1.41% per year, concordant with previous reports in a reallife exhaustive registry.