Login to Access Video or Poster Abstract: MP72-10
Sources of Funding: none

Introduction

To evaluate the association between body mass index (BMI) and survival outcomes in patients with non-metastatic RCC.

Methods

A single-institutional retrospective analysis was implemented on 2329 patients who underwent radical or partial nephrectomy for non-metastatic RCC from 2000 to 2014. Enrolled patients were grouped into normal (BMI <23kg/m2, n=705), overweight (BMI 23-24.9 kg/m2, n=648), and obese (BMI ?25kg/m2, n=976) according to BMI cut-offs for Asian population. Outcomes of interest included recurrence free survival (RFS), overall survival (OS), and cancer-specific survival (CSS). Survival curves for each BMI category were estimated and compared using the Kaplan-Meier method with log-rank test. The impact of BMI as continuous or categorical variables on survival outcomes was assessed with multivariable Cox proportional hazard models.

Results

Several clinico-pathological factors, including asymptomatic presentation, being female, lower transfusion rate, higher proportion of clear cell histology, and lower frequency of nodal invasion, were observed in association with obese group (all p<0.05). Obese group showed significantly better 5-year RFS (90.7% vs 84.9%, p<0.001), OS (91.8% vs 86.8%, p=0.002), and CSS (94.8% vs 89.4%, p=0.002) rates than normal patients. On multivariable analysis, BMI as continuous variable independently correlated with favorable RFS (hazard ratio [HR] 0.93; 95% confidence interval [CI] 0.89-0.97, p=0.002), OS (HR 0.95; 95% CI 0.91-0.99, p=0.033) and CSS (HR 0.91; 95% CI 0.86-0.97, p=0.002). In addition, multivariable analysis revealed overweight (HR 0.57; 95% CI 0.37-0.87, p=0.009) and obese patients (HR 0.58; 95% CI 0.39-0.87, p=0.009) were associated with significantly reduced risk of RCC related death compared to normal patients.

Conclusions

Our data suggest overweight and obesity defined as increasing BMI are generally related to favorable survival outcomes after nephrectomy for non-metastatic RCC. Further basic research will be required to discover the biological mechanisms explaining the positive correlation between high BMI and improved RCC survival.

Funding

none