Examining the Link Between Obesity and Multiple Myeloma

There may be a correlation between obesity and an increased risk of a blood disorder that may eventually lead to multiple myeloma, according to recent research published in the Journal of the National Cancer Institute.

Monoclonal gammopathy of undetermined significance (MGUS) is a precancerous blood disorder in which abnormal plasma cells produce many copies of an antibody protein. Su-Hsin Chang, Ph.D., assistant professor of surgery in the Division of Public Health Science at Washington University and first author of this study, explained that this protein is not harmful to most people, but it can “crowd out healthy cells in bone marrow and can damage other tissues.”

Because this condition often displays no symptoms and does not require treatment, it commonly goes undiagnosed. However, presence of MGUS does increase the risk for multiple myeloma in patients.

A recent study done at Washington University School of Medicine in St. Louis looked at data from U.S. Department of Veteran Affair’s database, where researchers found 7,878 patients, largely men, diagnosed with MGUS from October 1999 through December 2009. In this population, 39.8 percent of those patients were overweight and 33.8 percent were obese.

According to Chang, this is the first study to look at the link among all three factors: obesity, MGUS and multiple myeloma.

Of the patients who were overweight, 4.6 percent developed multiple myeloma when followed for a mean of 5.8 years. Of the patients who were obese, 4.3 percent (followed for a median of 5.9 years) saw progression to multiple myeloma. When compared to the 3.5 percent of patients at an average weight who developed cancer and were followed for a median of 5.2 years, the difference is statistically significant.

Patients who were overweight with MGUS had a 55 percent higher risk of progression to multiple myeloma, while patients who were obese had a 98 percent higher risk, than patients at an average weight.

Additionally, African-American men were more likely than Caucasian men to have their condition become cancerous.

As this was not a clinical trial, there could be no causal effect determined. However, Chang stated, “Our findings show that obesity can now be defined as a risk factor for developing multiple myeloma through this condition.” She went on, “We hope that our results will encourage intervention strategies to prevent the progression of this condition to multiple myeloma as soon as MGUS is diagnosed.”

She also clarified that this study did not necessarily “suggest screening for MGUS, regular check-ups can help physicians monitor whether MGUS is progressing to other disorders, including multiple myeloma.”

With confirmation from further trials, patients diagnosed with MGUS could prevent progression to multiple myeloma by maintaining a healthy weight. Chang is planning future studies, along with other researchers, including senior author Kenneth R. Carson, M.D., Ph.D., assistant professor of oncology, and Graham Colditz, M.D., Dr.P.H., a cancer expert as well as associate director of prevention and control at Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.

For those future studies, Chang hopes to look at “whether healthy weight loss is inversely associated with the progression of multiple myeloma in MGUS patients or how weight change plays a role in the progression of MGUS to multiple myeloma.”