Correlation of Body Mass Index with Overall Survival Among Patients with Metastatic Hormone-sensitive Prostate Cancer: Analysis of Patient-level Data from SWOG-1216

Although obesity has been associated with better overall survival (OS) among patients with metastatic castration-resistant prostate cancer, its association with OS has not been extensively explored in metastatic hormone-sensitive prostate cancer (mHSPC). We conducted a post hoc exploratory analysis of patient-level data from the SWOG-1216 trial to determine whether baseline body mass index (BMI) is associated with better OS among patients with mHSPC. SWOG-1216 was an open-label, phase 3 trial that randomized patients newly diagnosed with mHSPC 1:1 to either androgen deprivation therapy (ADT) with orteronel (experimental arm) or ADT with bicalutamide (control arm). Of 1279 patients included in the analysis, 12 (0.9%) were underweight, 252 (19.7%) had normal BMI, 958 (74.9%) were overweight, and 57 (4.5%) were obese. Age, Gleason score, extent of disease burden, the incidence of visceral metastases, and treatment allocation were similar among the groups (p > 0.05), while differences in baseline prostate-specific antigen and Zubrod performance status were observed (p < 0.05). Median OS was 2.4, 5.5, 6.6, and 6.8 yr in the underweight, normal, overweight, and obese groups, respectively. After adjusting for prognostic variables, high BMI was associated with better OS (HR for each increment in BMI category: 0.829, 5% CI 0.68-0.98; p = 0.029). These findings need to be validated in other phase 3 trials. PATIENT SUMMARY: We analyzed data from a clinical trial to evaluate the association between body mass index (BMI) and overall survival among patients with metastatic hormone-sensitive prostate cancer. We found that in this group of patients, the risk of death was lower for patients with higher BMI.