The Asco Post

African Americans Have Higher Prevalence of Multiple Myeloma Precursor Than Whites and Hispanics

By Jo Cavallo
Posted: 2/28/2014 2:44:17 PM
Last Updated: 2/28/2014 2:44:17 PM

Key Points:
  • Monoclonal gammopathy of undetermined significance (MGUS) is a precursor to the development of multiple myeloma.
  • A large population-based study has found that MGUS is significantly more common in African Americans compared with whites or Hispanics, as were features associated with a higher risk of progression to multiple myeloma.
  • There is a strong geographic disparity in the prevalence of MGUS between the North and Midwest (3.1%) and the South and West (2.1%) regions of the United States, suggesting an environmental component to the racial disparities.

A large population-based study by Landgren et al has found that African Americans are more likely to have a higher prevalence of monoclonal gammopathy of undetermined significance (MGUS), a precursor to the development of multiple myeloma, compared with whites or Hispanics. The study is published in Leukemia.

Researchers from the Mayo Clinic, the National Cancer Institute, and the Centers for Disease Control and Prevention examined stored serum samples from 12,482 individuals over the age of 50 from the National Health and Nutrition Examination Survey (NHANES) III or NHANES 1999-2004. The population breakdown included 2,331 African Americans, 2,475 Hispanics, 7,051 whites, and 625 classified as “other.” The main objective of the study was to define the prevalence and risk factors of MGUS in a large cohort representative of the United States population.

Study Method and Findings

The researchers performed agarose gel electrophoresis, serum protein immunofixation, serum-free light-chain assay, and M-protein typing on the serum samples. MGUS was identified in 365 participants (2.4%). Adjusted prevalence of MGUS was significantly higher (P < .001) in blacks (3.7%) compared with whites (2.3%; P = .001) or Hispanics (1.8%), as were characteristics that posed a greater risk of progression to multiple myeloma. The findings could help determine tailored screening and preventive strategies for different racial groups.

“We have known for a long time that there is a marked racial disparity in multiple myeloma, but the big question has been why that disparity exists,” Vincent Rajkumar, MD, a senior author of the study and Professor of Medicine at the Mayo Clinic in Rochester, Minnesota, said in a statement. “We suspected it may be genetic or it may be environmental. We also thought that the predisposing factor is more common, or it may be that the predisposing factor progresses to cancer much more quickly. We found that the answer is all of the above.”

Geographic Variation

In addition, when the researchers broke down the national numbers into geographic areas of the country, they found that the adjusted prevalence of MGUS was 3.1% and 2.1% for the North and Midwest vs the South and West regions of the United States, respectively (P = .052). “We would have missed this geographic difference if we hadn’t looked at the whole country,” said Dr. Rajkumar.

Dr. Rajkumar and his colleagues are now investigating the underlying causes of these geographic variations to determine if they can identify the genetic and environmental factors contributing to the risk of MGUS. They are also repeating their experiments in serum samples of individuals under the age of 50 to try and pinpoint when the risk of MGUS and progression to multiple myeloma begins.

According to the American Cancer Society, about 24,050 new cases of multiple myeloma will be diagnosed this year, and about 11,090 Americans will die.

Funding for this study was provided by the National Cancer Institute, the Jabbs Foundation, and the Henry J. Predolin Foundation.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.

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