Body mass index and overall survival in multiple myeloma.

e20007 Background: Elevated body mass index (BMI) is associated with a higher risk of multiple myeloma (MM), but its influence on survival is unclear. Studies evaluating BMI and mortality of MM have reported conflicting findings and most have limited data on clinical prognostic factors. We evaluated the associations between BMI at different life stages up to the time of diagnosis and overall survival (OS) in a cohort of newly diagnosed patients with MM. Methods: A total of 583 newly diagnosed MM patients were prospectively enrolled between 2010-2019 at the University of Chicago Medical Center. Epidemiology questionnaire and blood samples were collected at the time of diagnosis. We collected baseline clinical, laboratory, cytogenetic, and treatment data from electronic medical records. Vital status was ascertained using the National Death Index. Patients were followed through 31 December 2020 with an average follow-up length of 77.8 months. BMI was calculated using height and weight information collected from electronic health records and questionnaires. OS was defined as time from diagnosis until death from any cause. Chi-squared test and t-test were used to compare characteristics of patients by vital status. Hazard Ratios (HR) and 95% confidence intervals (CI) were derived from Cox proportional hazards models to examine the associations between BMI at different times and OS, adjusting for potential confounders. Stratified analyses were done to examine sex- and race-specific associations. Results: The median age at diagnosis was 63 years, 45% (n = 258) were female, and 27% (n = 150) were African Americans. Of the 572 MM patients, 176 (31%) deaths were identified during the follow-up. There was no significant association between elevated BMI at different time points (i.e., at diagnosis, 5 years before diagnosis, age 20, and maximum adulthood BMI) and OS after adjusting for age, race, sex, and prognostic variables (e.g., stage, serum lactate dehydrogenase levels). No association was found for both African Americans and European Americans. However, for women, obesity (BMI > = 30) at the time of diagnosis was associated with a better OS (HR = 0.25; 95% CI = 0.12-0.54 for obese vs. normal weight) whereas in men, obesity at the time of diagnosis was associated with worse OS (HR = 2.54; 95% CI = 1.18-5.49). Conclusions: We found no association between BMI and OS in MM, irrespective of race. Our data showed that, compared to subjects with normal BMI at the time of diagnosis, female patients with elevated BMI had better survival, whereas a higher BMI was associated with inferior OS among male patients. Our findings of an effect modification by sex are novel and warrant further investigations. These findings might have clinical significance because BMI is amenable to lifestyle modification.