Elevated Body Mass Index Is Associated with Improved Overall Survival in Castration-Resistant Prostate Cancer Patients Undergoing Prostate-Specific Membrane Antigen–Directed Radioligand Therapy

Abstract

In patients with prostate cancer scheduled for systemic treatment, being overweight is linked to prolonged overall survival (OS), whereas sarcopenia is associated with shorter OS. We investigated fat-related and body composition parameters in patients undergoing prostatespecific membrane antigen (PSMA)-directed radioligand therapy (RLT) to assess their predictive value for OS. Methods: Body mass index (BMI, in kg/m 2 ) and CT-derived body composition parameters (total, subcutaneous, visceral fat area, and psoas muscle area at the L3-L4 level) were determined for 171 patients scheduled for PSMAdirected RLT. After normalization for stature, the psoas muscle index was used to define sarcopenia. Outcome analysis was performed using Kaplan-Meier curves and Cox regression including fat-related and other clinical parameters (Gleason score, C-reactive protein [CRP], lactate dehydrogenase [LDH], hemoglobin, and prostatespecific antigen levels). The Harrell C-index was used for goodnessof-fit analysis. Results: Sixty-five patients (38%) had sarcopenia, and 98 patients (57.3%) had increased BMI. Relative to the 8-mo OS in normal-weight men (BMI , 25), overweight men (25 $ BMI . 30) and obese men (BMI $ 30) achieved a longer OS of 14 mo (hazard ratio [HR], 0.63; 95% CI, 0.40-0.99; P 5 0.03) and 13 mo (HR, 0.47; 95% CI, 0.29-0.77; P 5 0.004), respectively. Sarcopenia showed no impact on OS (11 vs. 12 mo; HR, 1.4; 95% CI, 0.91-2.1; P 5 0.09). Most of the body composition parameters were tightly linked to OS on univariable analyses, with the highest C-index for BMI. In multivariable analysis, a higher BMI (HR, 0.91; 95% CI, 0.86-0.97; P 5 0.006), lower CRP (HR, 1.09; 95% CI, 1.03-1.14; P , 0.001), lower LDH (HR, 1.08; 95% CI, 1.03-1.14; P , 0.001), and longer interval between initial diagnosis and RLT (HR, 0.95; 95% CI, 0.91-0.99; P 5 0.02) were significant predictors of OS. Conclusion: Increased fat reserves assessed by BMI, CRP, LDH, and interval between initial diagnosis and RLT, but not CT-derived body composition parameters, were relevant predictors for OS. As BMI can be altered, future research should investigate whether a high-calorie diet before or during PSMA RLT may improve OS.