Researchers have developed a risk score that can accurately predict the presence of adherent perinephric fat (APF) in patients with small renal masses planning to undergo partial nephrectomy.1

APF is a commonly encountered intraoperative challenge in partial nephrectomy, but researchers hypothesized that anticipation of this feature may improve preoperative risk assessment and assist in decision-making for the surgical approach. Therefore, researchers sought to develop and validate a score that predicted for the risk of APF based on preoperative clinical and radiological prognostic factors.

They retrospectively analyzed data from 495 patients that underwent open or minimally invasive partial nephrectomy. Of those, 19% presented with APF. Researchers found that diabetes mellitus (P = .009), perinephric fat thickness (P < .001), and perinephric stranding (P < .001) were predictors of encountering APF during the operation.

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Then, the researchers developed a risk score ranging from 0 to 4 based on the 3 aforementioned variables to predict for APF, which was defined as the presence of dense, adherent, or sticky perinephric fat at the time of dissection that did not require subcapsular dissection to isolate the tumor.

The risk score was then validated in 285 patients, of which 14.3% presented with APF. In this cohort, the risk score had a specificity of 92.2 and good discrimination of 0.84. There was also no statistically significant lack of calibration (P = .35).

“This score could aid current algorithms of preoperative risk assessment and impact surgical approach,” the investigators concluded.


  1. Borregales LD, Adibi M, Thomas AZ, et al. Predicting adherent perinephric fat with preoperative clinical and radiological factors in partial nephrectomy: development and validation of a risk score. J Clin Oncol. 2016; 34 (suppl 2S; abstr 497).