Precursor to Blood Cancer Puts Patients at Risk Indefinitely, Study Finds

Despite years of stability, patients with monoclonal gammopathy of undetermined significance (MGUS) are at risk of progressing to multiple myeloma or another blood cancer, according to a long-term follow-up study published in New England Journal of Medicine. MGUS usually causes no problems, but it is a precursor to cancer.

The researchers followed 1384 people with MGUS for a median of 34.1 years. The primary endpoint of the study was progression to multiple myeloma or to plasma-cell or lymphoid disorders. They also determined overall survival among patients according to MGUS subtype (IgM or non-IgM).

Overall, MGUS occurs in 3.2% of people age 50 and older, and 5.3% of those age 70 or older. While the study found that the overall risk of progression to cancer is just 1% each year, the risk persists indefinitely. During the follow-up, 11% of patients developed multiple myeloma or a related disease, which represented a risk that was 6.5 times as high as the risk in an age- and sex-matched background population.

Compared with the control population of Minnesota residents, patients with MGUS also had a shorter median survival of 8.1 years compared with 12.4 years for the control population of Minnesota residents.

“We also found that patients with monoclonal gammopathy of undetermined significance had shorter survival than comparable people without the condition,” S. Vincent Rajkumar, MD, a hematologist at Mayo Clinic and senior author of the study, said in a statement, “which raises the possibility there may be other disorders associated with monoclonal gammopathy of undetermined significance that still need further study.”

However, the researchers also found that risk of progression to multiple myeloma or a related disorder was less than the risk of death due to another cause, which lead the authors to decide that there is “limited data at present to indicate that screening for MGUS or monitoring improves outcomes in patients.”

While the researchers found that the death rate at 40 years among patients with MGUS was 11% owing to plasma-cell disorders, the death rate was 87% owing to non—plasma-cell disorders, such as cardiovascular and cerebrovascular diseases, as well as non–plasma-cell cancers.

The researchers recommend that patients who are being followed for MGUS also receive other, appropriate routine preventive services as they age.