ST. LOUIS — Obesity ranks high in the list of risk factors for the development of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). Could exposure to high body mass index affect the velocity of the monoclonal protein (M-spike) and serve as an indicator of the risk of that progression?
MGUS is an asymptomatic, non-malignant condition. About 20% of patients diagnosed with MGUS will eventually progress to multiple myeloma. Patients with MGUS have a 1% risk of progressing per year. All patients with MM previously had MGUS.
Researchers at the St. Louis VAMC, Washington University in St. Louis, and Saint Louis University knew from previous research that M-spike presence at MGUS diagnosis and high M-spike velocity in the year following MGUS diagnosis were associated with progression from MGUS to MM. They also understood that obesity increased the likelihood of progression as well. In a study presented at the 2023 American Society of Clinical Oncology annual meeting in Chicago, June 2-6, 2023, they sought to better understand the relationship between obesity and increasing M-spike levels.1
The team turned to the VA’s records to identify all veterans diagnosed with MGIS between 1999 and 2021 and confirmed the diagnosis. Then they determined whether the veteran progressed to smoldering MM—an intermediate stage between MGUS and MM—or to full-blown MM five or more years after MGUS diagnosis. Veterans without M-spike levels within a year before or after MGUS diagnosis were excluded, as were those lacking body mass index (BMI) data three years or more out from the diagnosis.
The team considered exposure to excess BMI to be that above 25 kg/m2 over the five years following MGUS diagnosis. A multivariate model estimated the association between excess BMI trajectory and M-spike trajectory, with covariates including BMI, M-spike level and age at MGUS diagnosis; sex, race, MGUS heavy chain subtype, and light-chain MGUS.
The final analysis included 6,757 veterans with an MGUS diagnosis. The team found a positive association between excess BMI trajectory and increasing M-spike trajectory (β = 0.005, p = 0.007). They noted that “increasing BMI over time following MGUS diagnosis was associated with increasing M-spike level. This further supports the relationship between obesity and weight gain in the pathway of MGUS to MM progression.”
- Liu L, Grandhi N, Wang M, Thomas TS, Kumar A, Sanfilippo KM, Colditz GA, Chang SH. Association between excess body mass index trajectory and change in monoclonal protein level in patients diagnosed with monoclonal gammopathy of undetermined significance. 2023 ASCO annual meeting. June 2-6, 2023. J Clin Oncol 41, 2023 (suppl 16; abstr 10538)
