Patients with monoclonal gammopathy of undetermined significance have an increased risk of developing blood clots, according to a recent study published in the European Journal of Haematology. Blood clots were also associated with poor survival in these patients.   

“Our findings underline the risk of VTE [blood cots] in the monoclonal gammopathies in general and might in this way serve to increase the awareness of this complication in myeloma patients,” stated Dr. Henrik Gregersen, of the Aalborg Hospital in Denmark and lead author of this study.

While some of the increased risk may be an innate feature of the disease, the researchers concluded that the numbers were not big enough to justify the use of medication to prevent clotting, such as aspirin or heparin, in patients with the precursor disease. Instead, they suggested patients be monitored for coexisting medical conditions that warrant the use of preventative medications.

Monoclonal gammopathy of undetermined significance (MGUS) is a blood disorder characterized by elevated levels of monoclonal protein. It is often found during testing for other disorders. Evidence suggests that MGUS may be a precursor of most cases of multiple myeloma (see related Beacon news). 

Three percent of Americans over the age of 50 are diagnosed with MGUS, 1 percent of whom are likely to develop multiple myeloma or other similar diseases.  The International Myeloma Working Group recently identified myeloma risk factors for patients with MGUS, including the amount of monoclonal protein, the type of monoclonal protein, the number of bone marrow plasma cells, and the free light chain ratio (see related Beacon news).

Recently, blood clots, or venous thromboembolism (VTE), have been identified as a complication of multiple myeloma.

Ten percent of newly diagnosed myeloma patients develop VTE while undergoing chemotherapy treatment. The risk of VTE is even higher for patients who receive a combination regimen of chemotherapy, steroids, and immunomodulatory agents, such as Revlimid (lenalidomide) and thalidomide (Thalomid) (see related Beacon news).

Several studies have been conducted to determine if MGUS patients share a similar increased risk of VTE as myeloma patients, but results have been inconsistent so far. 

Results are further complicated by the fact that most MGUS patients have additional medical conditions (called comorbidities) that may increase their risk of VTE.

“The comorbidity is high in patients with MGUS and many coexisting clinical conditions and diseases have been reported, including non-hematological cancers, chronic infections, neurological disorders, osteoporosis and fracture risk. All these diseases are also potential risk factors for VTE,” explained Dr. Gregersen.

As such, the goal of this study was to compare the risk and complications of VTE in a much larger and broader group of MGUS patients to the general population. 

A total of 1610 MGUS patients were enrolled in the study. The patients were followed until VTE occurred, their MGUS transformed into a cancerous condition or until they died. 

Researchers found that compared to the general population, MGUS patients enrolled in this study had a 37% higher risk of developing VTE.

The average time to VTE from the start of follow up was 5.6 years for MGUS patients and 6.2 years for the general population.

Among the MGUS patients, those with low B cell (cells that produce antibody), M-protein, monoclonal protein or light chain lambda (both proteins overproduced by B cells) levels were at increased risk for VTE.

Researchers also found that VTE was associated with poor survival in MGUS patients.  These finding confirmed those of a separate study while, in contrast, VTE has been found not to effect survival time in multiple myeloma patients.

For more information, please see the research article in the European Journal of Haematology (abstract).