Patients in a precancerous stage of multiple myeloma would be wise to avoid gaining extra weight, according to new research that shows being overweight or obese increases the risk that the condition progresses to cancer.
The study, “Obesity and the Transformation of Monoclonal Gammopathy of Underdetermined Significance to Multiple Myeloma: A Population-Based Cohort Study,” was published in the Journal of the National Cancer Institute.
Researchers at Washington University School of Medicine in St. Louis studied people with monoclonal gammopathy of undetermined significance (MGUS). This disorder, which affects plasma cells in the blood, is known to precede myeloma. But the condition often does not cause symptoms, and most people are not even aware they have it.
“The diagnosis is usually by accident, often driven by tests performed for the diagnosis or management of other conditions,” Su-Hsin Chang, PhD, an assistant professor of surgery at Washington University, said in a news release.
The team used data from a U.S. Department of Veterans Affairs database to identify patients diagnosed with MGUS. They analyzed data from 7,878 patients, most of whom were men, who were diagnosed with MGUS from October 1999 through December 2009.
The patients consisted of 39.8 percent who carried extra weight and 33.8 percent who were obese. The remaining patients were of normal weight. Obese, overweight, and normal weight patients were followed for a median of 5.9 years, 5.8 years, and 5.2 years, respectively.
Looking at how the different groups progressed, the team found that 4.3 percent of obese patients and 4.6 percent of overweight patients developed multiple myeloma. In normal-weight patients, the proportion was 3.5 percent.
Translating this to an increased risk of developing myeloma, obese MGUS patients had a 98 percent higher risk of progression to multiple myeloma compared to people with MGUS and a normal weight. For people who carry extra weight, the risk was somewhat lower — 55 percent — a difference that is still significant.
The study also demonstrated that African-American men were at a higher risk of developing myeloma than men of European descent.
“Although our study does not directly suggest screening for MGUS, regular check-ups can help physicians monitor whether MGUS is progressing to other disorders, including multiple myeloma,” Chang said.
The team hopes their findings will encourage weight-targeting interventions to prevent the progression of MGUS to multiple myeloma.