New Mayo Study Shows Higher Prevalence of MGUS, A Pre-Cancerous Blood Disorder, than Previously Suspected

Wednesday, March 29, 2006

ROCHESTER, Minn. — Mayo Clinic researchers have determined that the occurrence rate for monoclonal gammopathy of undetermined significance (MGUS) — a known precursor condition for multiple myeloma and other related blood disorders — is nearly twice as high as what has previously been reported. Study results will be available online March 30 in The New England Journal of Medicine.

"Several years ago we learned that MGUS will progress constantly over time to multiple myeloma or related disorders," says Robert Kyle, M.D., Mayo Clinic hematologist and the study's lead investigator. "We identified how high that risk actually is." Dr. Kyle's previous paper establishing the progression rate of MGUS is available at: http://content.nejm.org/cgi/content/full/346/8/564.

In the present study, Dr. Kyle and colleagues found that MGUS is present in 3.2 percent of the general population age 50 and older and in 5.3 percent of persons 70 or older. Prevalence increased with age, the highest rate being 8.9 percent in men age 85 and older. Previous studies reported prevalence rates ranging from 0.5 to 3.6 percent in the normal population, but none of them were conducted as a true population-based study — necessary for accurate prediction of prevalence within the general population. These previous findings led to the understanding that MGUS was found in about 3 percent of people age 70 or older, and about 2 percent of ages 50 to 70.

Dr. Kyle's team conducted this research to determine a more accurate statistic that would assist in developing preventive treatments as well as provide physicians with more precise diagnostic capabilities. "This will be the definitive source of information on the frequency of MGUS for many years to come and has some important implications for clinical care," he says. "Understanding the risk of progression and the actual prevalence allows physicians to better individualize a patient's care." Dr. Kyle and his fellow researchers say that this information will aid in reducing the potential number of diagnostic tests for elderly patients. It also has application in screening and prevention specifically designed to reduce mortality from myeloma.

MGUS is identified by an abnormal protein that is produced by plasma cells and progresses over time to multiple myeloma or another of a variety of rarer blood or bone cancers. The condition is defined by monoclonal (M) protein amounts in blood serum of three grams per deciliter (g/dL) or less (more would indicate multiple myeloma or another disorder), the absence of bone involvement, anemia, excess calcium in the blood, 10 percent or fewer plasma cells in the bone marrow, and absence of kidney failure related to the M protein.

All residents of Olmsted County, Minn., as of Jan. 1, 1995, age 50 and older were initially included in the study, but blood samples actually used in the study were obtained from 21,463 (77 percent). The participants were representative of the general population.

Dr. Kyle's fellow Mayo Clinic researchers included L. Joseph Melton III, M.D.; Terry Therneau, Ph.D.; S. Vincent Rajkumar, M.D.; Dirk Larson; Matthew Plevak; Janice Offord; Angela Dispenzieri, M.D.; and Jerry Katzmann, Ph.D. The study was funded in part by grants from the National Cancer Institute.

For more information on the research and treatment of monoclonal gammopathy visit www.mayoclinic.org/monoclonal-gammopathy/index.html.

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