The Relationship Between Visceral Obesity and the Clinicopathologic Features of Patients with Small Renal Masses

Introduction and Objectives: It is well known that adipose tissue plays a key role in the metabolic syndrome. We investigated whether visceral fat (VFA) and or subcutaneous fat (SQF) levels are associated with the tumor phenotype of small renal masses. Additionally, we sought to investigate the relationship between VFA and baseline renal function as measured by glomerular filtration rate. Materials and Methods: From 2002 through 2011, 144 patients undergoing minimally invasive partial nephrectomy were retrospectively reviewed by a radiologist for VFA and SQF fat measurements, using standard software. A third parameter, visceral adipose tissue percent (VAT%), was also calculated using the formula: (VAT%=[VFA/VFA+SQF]x100%). We used tertiles of VFA and SQF content to compare demographic and clinical characteristics. We also looked at VFA as a continuous variable. Associations between covariables were analyzed using multivariate logistic regression analysis and odds ratios with 95% confidence intervals. Results: Eighty-one patients had renal-cell carcinoma (RCC) and 30 patients had non-RCC pathology. On multivariate analysis, increasing BMI (p=0.023), VFA (p=0.048), VAT% (p=0.028), and Charlson comorbidity score (p=0.047) were significantly associated with worse preoperative Modification of Diet in Renal Disease (MDRD). In a subset multivariate analysis of the 81 patients with RCC, increasing VFA was statistically associated with worsening Fuhrman grade (p=0.017). Conclusions: VFA may be linked to the pathophysiology of renal function in patients evaluated for renal masses. Additionally, VFA may be associated with worsening tumor grades in patients with small-volume RCC. Interestingly, SQF did not play such a role. This small study proposes an interesting physiologic link between VFA and the biology of both kidney function and tumor histology. Larger studies are needed to corroborate our findings.