Introduction: Long term body composition changes after radical cystectomy (RCx) are unknown. Herein, we characterize changes in body composition over one year after RCx and determine predictors of unfavorable change in radiographic nutritional indices. Methods: CT images for 843 RCx patients from 2009-2017 were collected at baseline, 3 months, and 1 year. Artificial intelligence algorithms extracted two-dimensional axial skeletal muscle and adipose areas at the L3 level. Skeletal muscle index (SMI) and fat mass index (FMI) were calculated, and multivariable logistic regression models were performed to determine factors associated with unfavorable body composition change: absolute top tertile change in FMI and SMI. Results: Muscle and fat body parameters decreased from baseline to 3 months but increased from 3 months to 1 year (Figure 1). However, the distributions of changes in SMI and FMI across these timepoints (Figure 2) show that some patients were able to maintain muscle and fat mass after surgery. In the first 3 months, increasing age and higher BMI were associated with greater loss in FMI (odds ratio (OR) < 1, p<.05); while neoadjuvant chemotherapy was associated with increased gains (OR 1.5, p=.03). After 3 months, robotic surgery was associated with greater gains in FMI (OR 1.8, p=.03). In the first 3 months, on multivariable analysis, men (OR 2.06), increasing BMI (OR 1.08), neoadjuvant chemotherapy (OR 3.98), and any 30-day complications (OR 1.79) were associated with greater loss in SMI from baseline to 3 months (p <.05 for all). After 3 months, older patients had smaller gains in SMI (p <.05), as did patients with bladder cancer recurrences (p <.05). On the contrary, patients with continent diversion were associated with greater gains in SMI (p <.05). Conclusions: Long-term changes in body composition after RCx are common, and clinically relevant predictors of unfavorable body composition change were identified indicating a catabolic state. Individualized rehabilitation interventions based on these predictors warrants further study. SOURCE OF Funding: None.
