Monoclonal gammopathy of undetermined significance and risk of lymphoid and myeloid malignancies: 728 cases followed up to 30 years in Sweden

Blood. 2014 Jan 16;123(3):338-45. doi: 10.1182/blood-2013-05-505487. Epub 2013 Nov 12.


In 728 Swedish cases of monoclonal gammopathy of undetermined significance (MGUS), followed up to 30 years (median, 10 years), we estimated the cumulative risk of hematologic disorders originating from lymphoid and myeloid lineages. Using Cox regression models, we examined associations of demographic and laboratory factors with progression and determined the discriminatory power of 3 prediction models for progression. Eighty-four MGUS cases developed a lymphoid disorder, representing a cumulative risk of 15.4%. Multiple myeloma (MM) occurred in 53 patients, and the 30-year cumulative risk was 10.6%; an ∼0.5% annual risk. Three factors were significantly associated with progression: abnormal free light-chain (FLC) ratio (<0.26 or >1.65), M-protein concentration (≥1.5 g/dL), and reduction of 1 or 2 noninvolved immunoglobulin isotype levels (immunoparesis). A prediction model with separate effects for these 3 factors and the M-protein isotype had higher discriminatory power than other models, although the differences were not statistically significant. The 30-year cumulative risk for myeloid malignancies was <2%. Our study confirms that abnormal FLC ratio and M-protein concentration >1.5 g/dL, factors previously considered by Mayo Clinic researchers, are predictors for MM progression and suggests that separate consideration of immunoparesis and the Mayo Clinic risk factors could improve identification of MGUS patients at high risk for progression.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Area Under Curve
  • Cohort Studies
  • Disease Progression
  • Female
  • Follow-Up Studies
  • Hematologic Neoplasms / complications
  • Hematologic Neoplasms / diagnosis*
  • Humans
  • Immunoglobulin Light Chains / chemistry
  • Immunoglobulins / metabolism
  • Immunosuppressive Agents / therapeutic use
  • Lymphoma / complications
  • Lymphoma / diagnosis*
  • Male
  • Middle Aged
  • Monoclonal Gammopathy of Undetermined Significance / complications*
  • Monoclonal Gammopathy of Undetermined Significance / diagnosis*
  • Multiple Myeloma / complications
  • Multiple Myeloma / diagnosis*
  • Myeloma Proteins / metabolism
  • Proportional Hazards Models
  • Risk Factors
  • Sweden


  • Immunoglobulin Light Chains
  • Immunoglobulins
  • Immunosuppressive Agents
  • Myeloma Proteins
  • multiple myeloma M-proteins