From Mayo Clinic
Mayo Clinic study defines patients at greater risk for developing multiple myeloma and related bone marrow cancers Study also first to identify reliable predictors for disease progression
ROCHESTER, MINN. -- A Mayo Clinic study, published in the current edition of New England Journal of Medicine, has defined for the first time within a large population the rate at which patients with a monoclonal protein (M-protein) in their blood develop multiple myeloma, a fatal cancer of the bone marrow.
This study of 1,384 patients also is the first to identify reliable predictors for determining the rate of progression of monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma or related cancers.
"The significance of this study is that it now enables physicians to identify which patients are at greater risk for developing multiple myeloma, follow these patients and begin treatment before serious complications occur," says Robert Kyle, M.D., a Mayo Clinic hematologist and lead researcher on this study. "The goal is to achieve better treatment results and to obtain a better quality of life for the patient."
Unregulated growth of plasma cells in the bone marrow produces the abnormal M-protein. Patients with an M-protein in their blood, but without evidence of multiple myeloma, macroglobulinemia or primary amyloidosis, are considered to have MGUS, a condition that is a precursor to multiple myeloma or related cancers. MGUS is present in approximately two percent of Americans age 50 and older and about three percent of people older than age 70.
The study found the risk of progression of MGUS to multiple myeloma or related cancers is approximately one percent per year. The size of the abnormal M-protein was identified as the most important predictor for progression to malignancy. The progression rate at 20 years was found to be 14 percent for patients with very small protein levels, compared to 60 percent for patients with the highest levels of the M-protein.
"Since there is still no means to prevent or cure multiple myeloma, research on MGUS is important because it is the precursor condition to the more serious malignancy of myeloma," says Dr. Kyle.
Multiple myeloma is a cancer of the protein-producing plasma cells in the bone marrow. Currently more than 14,000 people in the United States are diagnosed with the cancer each year and 12,000 patients die from it. The cancer generally affects people age 50 and older. The average life expectancy of patients with this cancer is three to four years.
Dr. Kyle has researched MGUS and multiple myeloma for more than 40 years at Mayo Clinic. In this study, he followed the nearly 1,400 patients with MGUS over a 35-year period. The patients, all living in southeastern Minnesota, had been diagnosed with MGUS at Mayo Clinic between 1960 and 1994. In the study, 115 of the 1,384 patients with MGUS progressed to multiple myeloma or another related cancer of the bone marrow.
The study further found that patients continued to be at risk for progression even after 25 years or more of stable MGUS.
"Unfortunately, MGUS does not go away," says Dr. Kyle. "Once a patient is diagnosed with it, the patient almost always has it."
MGUS is usually diagnosed when patients undergo laboratory testing for various unrelated health problems. Dr. Kyle and the Mayo Clinic hematologists do not recommend that people be screened for the M-protein. Instead they suggest that physicians monitor patients diagnosed with MGUS through annual blood testing for the lifetime of the patient involved.