High BMI in Early Adulthood Increased Myeloma Risk

A large prospective analysis of three large cohorts found a positive link between risk for myeloma and cumulative average young adult and adult BMI.

Having a high body mass index (BMI) in young adulthood and later adulthood was associated with an increased risk for multiple myeloma, according to results of a study published in the British Journal of Cancer.

“Our findings support the growing body of literature demonstrating that a high BMI both early and later in adulthood is associated with the risk of multiple myeloma, and suggest that maintaining a healthy body weight throughout life may be an important component to a much-needed multiple myeloma prevention strategy,” wrote Catherine R. Marinac, PhD, of Dana-Farber Cancer Institute, and colleagues.

According to the study, obesity has been identified as one of the only modifiable risk factors for multiple myeloma.

“The IARC [International Agency for Research on Cancer] consensus report found compelling evidence that an absence of excess body fatness in adulthood has a preventative association with multiple myeloma and asserted that mechanistic evidence supports a causal cancer-preventive effect of weight loss on most cancers,” the researchers wrote. “To date there is little data on multiple myeloma risk in relation to weight and/or BMI changes in adulthood, a question that may be particularly relevant to MGUS [monoclonal gammopathy of undetermined significance] patients, given the lack of strategies for minimizing progression to malignancy.”

In order to find out more about the association between obesity and myeloma, Marinac and colleagues used data from the Nurses’ Health Study, Health Professionals Follow-Up Study, and the Women’s Health Study to look at measures of cumulative average BMI, change in BMI since young adulthood, and cumulative average physical activity and walking.

In the three study cohorts, 575 cases of myeloma were identified. The mean BMI was between 23.8 and 25.8 kg/m2 at baseline and from 21.3 to 23.0 kg/m2 at young adulthood.

The researchers found a positive link between risk for myeloma and cumulative average adult BMI and young adult BMI. Each 5 kg/m2 increase in cumulative average adult BMI was associated with a 17% increased risk for myeloma (hazard ratio [HR], 1.17; 95% CI, 1.05–1.29). In addition, each 5 kg/m2 increase in young adult BMI was associated with almost a 30% increased risk for myeloma (HR, 1.28; 95% CI, 1.12–1.47).

Change in BMI since young adulthood and cumulative physical activity and walking were not significantly associated with risk for myeloma.

“Our findings, which did not distinguish intentional from unintentional causes, suggest that irrespective of starting BMI in young adulthood, individuals who subsequently reduced their BMI or weight may have had a decreased risk of multiple myeloma,” the researchers wrote. “These data, combined with the mechanistic evidence outlined in the IARC report, suggest that weight loss may confer an added benefit for multiple myeloma prevention.”