Devascularized Parenchymal Mass Associated with Partial Nephrectomy: Predictive Factors and Impact on Functional Recovery

Purpose: Parenchymal mass loss is the predominant factor associated with functional outcomes after partial nephrectomy. It is primarily due to excised and/or devascularized parenchymal mass. We evaluated the importance of excised and devascularized parenchymal mass relative to functional recovery after partial nephrectomy. Materials and Methods: In 168 patients who underwent partial nephrectomy the necessary studies were done to determine excised and devascularized parenchymal mass, and evaluate parenchymal mass changes and functional loss of the operated kidney. Parenchymal mass loss in the ipsilateral kidney was measured on contrast enhanced computerized tomography less than 2 months before and 3 to 12 months after partial nephrectomy. Excised parenchymal mass was estimated by subtracting tumor volume from specimen volume. Devascularized parenchymal mass was defined as total parenchymal mass loss minus excised parenchymal mass. We used the Pearson correlation to evaluate relationships between glomerular filtration rate preservation and parenchymal mass loss. Multivariable analysis was done to assess factors associated with devascularized parenchymal mass. Results: Median tumor size was 3.4 cm and median R.E.N.A.L. (radius, exophytic/endophytic tumor properties, nearness of tumor to collecting system or sinus, anterior/posterior and location relative to polar lines) score was 7. Warm and cold ischemia was used in 100 and 68 patients, respectively. Median excised parenchymal and devascularized parenchymal mass was 9 and 16 cm 3, respectively (p < 0.001). Total parenchymal mass loss and devascularized parenchymal mass were associated strongly with glomerular filtration rate preservation in the operated kidney (each r >= 0.55, p < 0.001). However, excised parenchymal mass was only weakly associated with functional outcomes (r = 0.23). The preoperative glomerular filtration rate and endophytic status were associated with devascularized parenchymal mass on multivariable analysis. Conclusions: To our knowledge we report the first study to specifically evaluate the relative contributions of devascularized and excised parenchymal mass to functional recovery after partial nephrectomy. Our study suggests that devascularized parenchymal mass has more impact, which may have implications regarding surgical technique. Prospective study is required to further evaluate the relative contributions of excised and devascularized parenchymal mass in various settings.