Body size and risk of multiple myeloma in the Black Women's Health Study

Obesity is an established risk factor for multiple myeloma (MM). Relatively few prior studies, however, have evaluated associations in Black populations.

Among 55,276 participants in the Black Women's Health Study, a prospective U.S. cohort established in 1995, we confirmed 292 incident diagnoses of MM over 26 years of follow-up. Multivariable Cox proportional hazard models, adjusted for age and putative MM risk factors, were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of usual body mass index (BMI), BMI at age 18, height, and waist-to-hip ratio with MM.

Compared to women with a usual adult BMI < 25 kg/m², the HR associated with a usual adult BMI ≥ 35 kg/m² was 1.38 (95% CI: 0.96, 1.98). For early adult BMI, the HR comparing women with BMI ≥ 25 vs. <25 kg/m² was 1.57 (95% CI: 1.08, 2.28). Women who were heavy in both early and later life had the highest risk compared to those who were lean at both time points (HR: 1.60; 95% CI: 1.02, 2.52). Height was also associated with the risk of MM; the HR per 10 cm was 1.21 (95% CI: 1.02, 1.43).

These results indicate that high early adult BMI is associated with a 57% increased risk of MM in Black women and potentially highlight the importance of weight control as a preventive measure.