Background: Multiple myeloma (MM) risk increases with higher adult body mass index (BMI). Emerging evidence also supports an association of young adult BMI with MM. We undertook a pooled analysis of eight case-control studies to further evaluate anthropometric MM risk factors, including young adult BMI. Methods: We conducted multivariable logistic regression analysis of usual adult anthropometric measures of 2,318 MM cases and 9,609 controls, and of young adult BMI (age 25 or 30 years) for 1,164 cases and 3,629 controls. Results: In the pooled sample, MM risk was positively associated with usual adult BMI; risk increased 9% per 5-kg/m2 increase in BMI (odds ratio [OR]=1.09, 95% confidence interval [CI]= 1.04-1.14; p=0.007). We observed significant heterogeneity by study design (p=0.04), noting the BMI-MM association only for population-based studies (p-trend=0.0003). Young adult BMI was also positively associated with MM (per 5-kg/m2; OR=1.2, 95% CI=1.1-1.3; p=0.0002). Further, we observed strong evidence of interaction between younger and usual adult BMI (p-interaction <0.0001); we noted statistically significant associations with MM for persons overweight (25-<30 kg/m2) or obese (30+ kg/m2) in both younger and usual adulthood (v. individuals consistently <25 kg/m2), but not for those overweight or obese at only one time period. Conclusions:BMI-associated increases in MM risk were highest for individuals who were overweight or obese throughout adulthood. Impact:These findings provide the strongest evidence to date that earlier and later adult BMI may increase MM risk and suggest that healthy BMI maintenance throughout life may confer an added benefit of MM prevention.
- Received September 27, 2016.
- Revision received January 23, 2017.
- Accepted January 30, 2017.
- Copyright ©2017, American Association for Cancer Research.