Abstract
OBJECTIVE: To evaluate the impact of perinephric fat thickness and stranding around the unaffected kidney on progressive chronic kidney disease (CKD) and renal cell carcinoma (RCC) outcomes after radical nephrectomy. METHODS: We conducted an observational cohort study of 1276 patients with RCC who underwent radical nephrectomy at Mayo Clinic between January 1, 2000, and December 31, 2021. Regression models assessed the risk of progressive CKD and noncancer and cancer mortality with lateral and posterior fat thickness and perinephric fat stranding, adjusting for age, sex, and comorbidities. The Mayo Adhesive Probability (MAP) score was generated by summing posterior fat thickness score and perinephric stranding grade. Progressive CKD was defined as onset of dialysis, kidney transplant, sustained estimated glomerular filtration rate of less than 10 mL/min per 1.73 m(2), or sustained 40% decline from the postnephrectomy new baseline estimated glomerular filtration rate. RESULTS: Of 1276 patients, there were 52 progressive CKD events, 258 noncancer deaths, and 129 cancer deaths. Thick or diffuse fat stranding (type 2) was associated with progressive CKD (hazard ratio [HR], 10.79; 95% CI, 4.31 to 27.05; P<.0001). Thicker lateral and posterior perinephric fat was associated with a reduced risk of cancer mortality (HRs, 0.60 [95% CI, 0.48 to 0.75; P<.0001] and 0.74 [95% CI, 0.60 to 0.92; P=.005]). Higher MAP score was associated with increased risks of noncancer mortality (HR,1.74; 95% CI, 1.30 to 2.31; P=.0002) but with reduced risks of cancer mortality (HR, 0.48; 95% CI, 0.29 to 0.78; P=.003). CONCLUSION: Fat stranding in the remaining kidney is associated with progressive CKD. Elevated MAP score is associated with increased noncancer mortality and reduced RCC mortality.