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

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

Methods: 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.

Results: 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).

Conclusions: 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.