Presentation Authors: Anand Badri*, Philadelphia, PA, Andrew McIntosh, Houston, TX, Linda Hsu, Samuel Weprin, Tianyu Li, Richard Greenberg, Rosalia Viterbo, Marc Smaldone, David Chen, Robert Uzzo, Mohammed Haseebuddin, Alexander Kutikov, Philadelphia, PA
Introduction: Most recent AUA guidelines suggest that an expected drop of estimated glomerular filtration rate (eGFR) below 45 ml/min/1.733 upon radical nephrectomy (RN) should guide decision-making between RN and partial nephrectomy (PN) in patients with anatomically complex tumors. However, limited clinical tools are available to help with this assessment. Here, we examine the correlation between nuclear renal scan (NRS) -measured split renal function (nSRF) and renal parenchyma anatomic-measured (volumetric-estimated) split renal function (aSRF) in patients who underwent RN. We further assess the predictive value of nSRF and aSRF in anticipating post-operative eGFR decline after RN.
Methods: From our prospectively-maintained renal database, we identified patients with an enhancing renal mass who had both NRS and multiphase CT performed prior to RN. The average of three varying formulations for calculated renal parenchymal volumes was utilized. aSRF was determined by the ratio of the residual volume (parenchymal volume minus tumor volume) of the diseased kidney to the anatomic-measured total volume of both kidneys. Relationship of the ratio of aSRF to nSRF was examined at increasing tumor sizes to assess for over-estimation or under-estimation of SRF based on the calculated r-value. Spearman correlation coefficients were obtained between decline in eGFR and nSRF/aSRF.
Results: 37 patients were identified meeting criteria (median age 59 yrs [IQR 53-70], median pre-operative eGFR 73.83 ml/min/1.733 [IQR 59.85-94.19 ml/min/1.733]). Median maximum tumor diameter was 3.7 cm (IQR 1.7-4.6 cm) and median numerical RENAL nephrometry score was 10 (IQR 8-11). There was a significant and negative correlation with increasing tumor size to the ratio of aSRF to nSRF (r = -0.58, p = 0.0005) (Figure 1). Median post-RN change in eGFR was -23.66 ml/min/1.733 (IQR 11.22-36.44 ml/min/1.733). No significant correlation was identified between total (p=0.99) or residual volume (p=0.87) of diseased kidney, tumor volume (p=0.96), aSRF (p=0.34), or nSRF (p=0.4) and degree of eGFR decline.
Conclusions: NRS overestimates SRF of affected kidneys as renal tumor size increases. Importantly, eGFR following RN cannot be reliably predicted based on available imaging modalities that assess pre-operative SRF.