Correlation of body mass index (BMI) with survival outcomes in patients (pts) with metastatic hormone-sensitive prostate cancer (mHSPC): Analysis of patient (pt)-level data from SWOG 1216 study.

5081Background: Obesity has been associated with improved survival outcomes in metastatic castration-resistant prostate cancer (PMID: 34226662). However, association of obesity with survival has not been reported in mHSPC setting. Herein we report the correlation of BMI with survival outcomes from patient level data from phase III study, SWOG 1216 which randomized pts with mHSPC in 1:1 to ADT + bicalutamide or ADT + orteronel. Methods: Inclusion: all pts treated on SWOG 1216 study with available BMI. Overall survival (OS) was summarized by median survival and its 95% confidence interval (CI). Multivariate analysis for OS was conducted using Cox proportional hazard model with categorized BMI as a continuous variable, and adjusted for treatment arm, disease burden, Gleason score, log 2 PSA, age and Zubrod performance status. All analysis was conducted using R v4.2.1. Results: Of 1279 pts, 12 were underweight, 252 had normal BMI, 958 were overweight and 57 were obese. Median age was 67.8 (IQR: 61.9, 73.9) years, no visceral metastases (88%) and baseline log2 median PSA of 4.89 (IQR: 3.27, 6.76). All four BMI cohorts had similar age, Gleason score, extensive disease burden, liver metastases and treatment allocation (p>0.05). Differences in baseline PSA and Zubrod performance status were observed between BMI cohorts (p<0.05). The OS (in years) in underweight, normal, overweight and obese cohorts was 1.8, 4.4, 6.5 and 4.8 for bicalutamide arm and 2.8, 5.7, not reached (NR) and NR for orteronel arm, respectively. After adjusting for prognostic variables, multivariate analysis confirmed that high BMI is associated with better OS (HR=0.82, 95% CI: 0.68-0.98; p=0.029) (Table). Conclusions: Our results show that as categorized BMI increased, the risk of death decreased in pts with mHSPC. These data warrant external validation in other randomized phase III studies and can help counseling and prognostication of patients with mHSPC in the clinic. Funding: NIH/NCI grants CA180888, CA180819, and in part by Millennium Pharmaceuticals (Takeda Oncology Company). Clinical trial information: NCT01809691.