Robert Kyle, M.D., is a pioneer in the study of blood disorders. His work documenting patient histories, archiving blood samples and observing vast numbers of patients with plasma cell proliferative disorders has greatly contributed to the understanding these conditions and changed the practice of medicine. Dr. Kyle’s work has led to the classification of these disorders into groups:
- Benign — monoclonal gammopathy of undetermined significance
- Intermediate — smoldering multiple myeloma
- Severe — multiple myeloma
Now, Dr. Kyle, and other researchers at Mayo Clinic have published a new study that sheds light on the presence and evolution of monoclonal gammopathy of undetermined significance (MGUS) in the general population.
MGUS is a blood disorder that occurs when there is over abundance of one particular protein – M protein — in bone marrow. In rare cases MGUS can be a precursor to cancer, such as, multiple myeloma or other serious blood disorders.
The first-of-its-kind study makes use a 40-year history of research on MGUS and multiple myeloma to describe how people move through a series of states beginning with no disease to the development of MGUS and possibly to the development of cancer. To do this, researchers used data from multiple Mayo Clinic registries including the Rochester Epidemiology Project.
Researchers posited that if almost no one dies of MGUS and the number of people in the population with MGUS changes very little with age — both numbers are well known — then the number of new cases per year must be small. Secondly, that if there are a lot of people with MGUS but almost no new cases, then most people must have had the condition for some time. Their challenge was to quantify the small number of new cases and the amount of time that people had lived with the condition. Their finding on the amount of time was a surprise.“We found on average that most people when diagnosed had MGUS for 10 years,” said Terry Therneau, Ph.D., lead author of the study. “Over half of women diagnosed with MGUS at 70 years had the condition for more than 10 years, including 28% for more than 20 years. An estimated 55% of men diagnosed with MGUS at 70 years have had the condition for more than 10 years and 31% had it for more than 20 years.”
Other findings included: the annual incidence of MGUS in men is 120 per 100,000 at age 50, which increases to 530 per 100,000 at age 90. The annual incidence in women is 60 per 100,000 at age 50 years, which increases to 370 per 100,000 at age 90.
“Most research studies will provide a targeted look at one particular part of the disease process and simply cannot step back to view the whole,” says Dr. Therneau. “It’s like trying to deduce a house from pictures of one room. This study gives us a picture of the whole house.”
The study is available in the online edition of the journal Mayo Clinic Proceedings.