Laura AB et al. – This study investigated the 3 obesity–defining metrics for better examination of the associations between abdominal fat and generalized obesity with renal tumor stage, grade, or R.E.N.A.L. nephrometry score. The results of the study suggested that obesity measured by waist circumference (WC), but not body mass index (BMI) or retrorenal fat (RRF) was associated with increased renal mass complexity. Both high WC and BMI associated with lower–grade tumors exhibited a different Tumor Fuhrman grade trend. This indicates that WC and BMI are not interchangeable obesity metrics. However, further evaluation of RCC–specific outcomes using WC versus BMI is required for better understanding of the complex relationship between general and abdominal obesity and RCC characteristics.

Methods

• A prospective cohort study of subjects (N = 99) with renal masses undergoing resection and no evidence of metastatic disease, was performed and obesity was assessed using BMI, WC, and RRF pad distance.
• Preoperative computed tomography (CT) or magnetic resonance imaging (MRI) were used to calculate R.E.N.A.L. nephrometry scores.
• Associations between obesity metrics and nephrometry score, tumor grade, and tumor stage were identified using univariate and multivariate analyses.

Results

• Of the 99 subjects, surgery was partial nephrectomy in 51 individuals and radical nephrectomy in 48 individuals.
• Benign masses were reported in 11 patients and renal cell carcinoma (RCC) was reported in 88 patients (20 had stage T3 disease).
• A positive correlation was observed between WC and nephrometry score even after controlling for age, sex, race, and diabetes status (P = .02), but no positive correlation was observed between BMI and RRF (P = .13, and P = .57, respectively).
• T2/T3 subjects showed a higher WC compared to subjects with benign masses (P = .03) and subjects with Fuhrman grade 1 and 2 tumors had higher BMI (P<.01) and WC (P = .04) than subjects with grade 3 and 4 tumors.