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Multiple Myeloma and MGUS

Multiple myeloma is a rare plasma cell cancer, and incidence rates among African Americans are about twice those among whites in the United States. Rates among Hispanics are similar to those among whites, whereas rates among Asian/Pacific Islanders are substantially lower. The reasons for the excess among African Americans are not known.

Multiple Myeloma and Monoclonal Gammopathy of Undetermined Significance

Monoclonal gammopathy of undetermined significance (MGUS), a benign disorder with elevated monoclonal immunoglobulin levels, is a predisposing risk factor for multiple myeloma. DCEG investigators have conducted several studies examining the etiology of MGUS and its progression to myeloma.

  • National Health and Nutrition Examination Survey (NHANES) – This is the first comprehensive survey of MGUS among Hispanics in the U.S. The survey evaluated approximately 8,000 African Americans; 3,000 Hispanics; and 1,000 whites in the U.S.
  • Agricultural Health Study – This cohort study assessed the risk of MGUS in male pesticide applicators. The prevalence of MGUS among pesticide applicators was twice that in a population-based sample of men from Minnesota.
  • A study based on the Southern Community Cohort Study (SCCS) screened African-American and white women of similar socio-economic status for MGUS in relation to obesity and race. There was a two-fold excess of MGUS among African Americans compared to whites. Obesity was linked to MGUS, similar to its effect on myeloma.
  • Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial – This study identified subjects who developed myeloma and who had pre-diagnostic serum samples available. An asymptomatic MGUS stage consistently preceded myeloma.
  • U.S. Veterans cohort – This cohort study quantified prevalence of MGUS and subsequent risk of myeloma among 4 million African-American and white male veterans admitted to Veterans Affairs hospitals. Results indicated that the express risk of myeloma in African Americans stems from an increased risk of MGUS rather than an increased risk of progression from MGUS to myeloma. Various types of immune-mediated conditions might act as triggers for myeloma/MGUS development.