High BMI in early and late adulthood is a risk factor for MM

In order to improve prevention of Multiple Myeloma (MM), identifying risk factors is essential. Currently, the most established risk factors are non-modifiable factors such as old age, male gender, African descent, and a family history of hematologic malignancies. Although a few epidemiologic studies have shown a positive association between obesity and MM risk, there is still little known about the impact of body mass index (BMI) in earlier and later life and the associated risk for MM.

Catherine R. Marinac from the Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, US, and colleagues, analyzed data from three large prospective cohorts to assess whether changes in BMI or physical activity, affect the risk of developing MM. The results of this study were published in the British Journal of Cancer in April 2018.

Study design:

• Data was collected from three cohorts: Nurses’ Health Study (NHS), Health Professionals Follow-up Study (HPFS), and Women’s Health Study (WHS)
• Variables assessed included young adult body mass index (BMI), cumulative average BMI, BMI change since young adulthood, and cumulative average physical activity and walking
• MM risk assessment was performed using Cox proportional hazard models

Patient characteristics:

Table 1. Patients characteristics of the Nurses’ Health Study (NHS), Health Professionals Follow-up Study (HPFS) and Women’s Health Study (WHS) cohorts.

(MET-h was used to assess physical activity and is a measure of total metabolic equivalent hours of all activity including walking, per week)

Key findings:

• Incidence of MM = 205 men (in the HPFS); 370 women (in two cohorts: NHS = 325, WHS = 45)
• A positive link between MM risk and both the cumulative average adult BMI and young adult BMI was observed
• Male gender gave a slightly stronger association with increased risk but wasn't statistically significant
• Pooled meta-analysis showed:
  • A significant (17%) increased risk of MM is associated with each 5 kg/m² increase in cumulative average adult BMI (HR = 1.17; 95% CI; 1.05–1.29)
  • A 30% increase in MM risk is associated with 5 kg/m² increase in young adult BMI (HR = 1.28; 95% CI; 1.12–1.47)
• An association was observed between the change in BMI since young adulthood and MM risk, although was not statistically significant (P = 0.10)
• A significant 4% increased risk of developing MM was associated with each 5kg increase in weight change since young adulthood (pooled HR = 1.04; 95% CI; 1.00–1.08; P = 0.03)
• No increased risk was observed for physical activity variables

This study, therefore, confirms a significant association between high BMI in early and late adulthood and an increased risk of developing MM. This finding ties in with previous research showing that obesity is a risk factor for progression from monoclonal gammopathy of undetermined significance (MGUS) to MM – read here. Obesity is, therefore, a modifiable factor for patients with MM, with well-managed weight control part of a valid strategy for reducing the risk of developing MM in patients with MGUS.