Prognostic significance of preoperative kidney volume for predicting renal function in renal cell carcinoma patients receiving a radical or partial nephrectomy

Follow-up study of unilateral renal function after nephrectomy assessed by glomerular filtration rate per functional renal volume

Background

To evaluate the clinical usefulness of estimated glomerular filtration rate (eGFR) divided by functional renal volume (FRV) measured by three-dimensional image reconstruction (eGFR/FRV) for the prediction of functional outcomes after nephrectomy.

Methods

Eighty-three patients who underwent nephrectomy were enrolled. The FRV of each patient was measured before surgery. Preoperative medical information on proteinuria, blood pressure, blood glucose level, body mass index (BMI), hemoglobin level and serum cholesterol level were also obtained. We evaluated the relationships between eGFR/FRV and each of these parameters before surgery. We also assessed the potential relationship between eGFR/FRV and the 3-year postoperative eGFR. Stepwise multiple regression analyses were conducted to elucidate independent factors.

Results

The median FRV and eGFR were 310.15 cm³ and 79.0 ml/min/1.73 m² before surgery, respectively. The correlation between FRV and eGFR was statistically significant (r = 0.465, P < 0.001). The median eGFR/FRV was 0.24 ml/min/1.73 m²/cm³. Stepwise multiple regression analysis showed that the independent parameters (multiple correlation coefficient, r = 0.389, P = 0.031) associated with eGFR/FRV were proteinuria, BMI, age and hypertension. Proteinuria was statistically associated with eGFR/FRV, and the independent parameters (multiple correlation coefficient, r = 0.694, P < 0.001) associated with the 3-year postoperative eGFR were age, BMI and eGFR/FRV. The eGFR/FRV was statistically associated with the 3-year postoperative eGFR (r = 0.559, P < 0.001).

Conclusion

The present results demonstrated that patients with proteinuria are expected to have a lower eGFR/FRV than those without proteinuria. The present study also supports the notion that eGFR/FRV is the primary determinant of the long-term functional outcome after nephrectomy. It should be taken into consideration that patients with a low eGFR/FRV may develop chronic kidney disease after nephrectomy.

Predictive factors for the development of chronic renal insufficiency after renal surgery: a multicenter study

PURPOSE

To evaluate which factors affecting changes in postoperative renal function after conducting radical nephrectomy or partial nephrectomy.

METHODS

Data on patients who underwent operations for renal cell carcinoma between 2000 and 2010 at multiple institutions were collected. Patient characteristics including preoperative estimated glomerular filtration rate (EGFR) were investigated, and types of surgery and postoperative results were evaluated. Renal insufficiency was defined as an EGFR <60 ml/min/1.73 m(2). Cox proportional hazard regression analysis was used to investigate which factors were associated with chronic renal insufficiency after surgery.

RESULTS

A total of 2,454 patients were included for evaluation; 1,502 patients underwent radical nephrectomy, whereas 952 patients underwent partial nephrectomy. The mean follow-up period was 44.48 ± 27.04 months (range, 12-120 months). Factors affecting EGFR were age, diabetes, hypertension, surgical procedure, and preoperative creatinine level (p < 0.001). Factors affecting postoperative renal insufficiency were age, surgical procedure, serum creatinine level, and EGFR.

CONCLUSION

The risk for developing post-nephrectomy renal insufficiency in patients who underwent radical nephrectomy was higher than those who underwent partial nephrectomy. Factors affecting post-nephrectomy renal insufficiency were age, preoperative serum creatinine level, and preoperative EGFR. In addition to radical nephrectomy, patient >58 years with a preoperative serum creatinine >1.03 mg/ml, and EGFR <73 ml/min/1.73 m(2) had a higher probability of developing post-nephrectomy chronic renal insufficiency.

Small tumour size is associated with new-onset chronic kidney disease after radical nephrectomy in patients with renal cell carcinoma

BACKGROUND

To investigate the impact of tumour size on postoperative glomerular filtration rate (GFR) in patients undergoing radical nephrectomy (RN) for renal cell carcinoma (RCC).

METHODS

We retrospectively identified 1371 patients who underwent RN between 1995 and 2010. Serum creatinine levels were measured preoperatively, within 7days of RN, at 3months, 1 and 3years. We divided patients into three groups based on tumour size: A: ⩽4cm, B: 4-7cm, C: >7cm. The changes in GFR were compared and multivariate logistic regression was used to analyse the predictive value of tumour size for new-onset chronic kidney disease (CKD, GFR<60mL/min/1.73m(2)).

RESULTS

The preoperative GFR was significantly different among the three groups (A: 83.0, B: 82.0, C: 79.4ml/min/1.73m(2), P=0.040). The decrease in GFR from preoperative to within 7days was greater in group A than in groups B and C (28.2 versus 24.2 versus 18.5ml/min/1.73m(2), P<0.001). The GFR at 1year postoperative was lower in group A than in group C (58.4 versus 61.5ml/min/1.73m(2), P=0.009), in contrast to preoperative GFR. The incidence of GFR decrease >30% was higher in Group A than in Groups B and C at 1year (52.4% versus 41.5% versus 33.7%, P<0.001). On multivariate analysis Groups A and B had a 2.37-fold (95% confidence interval (CI) 1.56-3.60, P<0.001) and 2.24-fold (95% CI 1.49-3.38, P<0.001) higher risk of new-onset CKD compared with Group C.

CONCLUSIONS

Small tumour size is associated with CKD after RN. Partial nephrectomy should be considered in patients with tumour size 7cm or less.

A simple method to estimate renal volume from computed tomography

INTRODUCTION

Renal parenchymal volume can be used clinically to estimate differential renal function. Unfortunately, conventional methods to determine renal volume from computed tomography (CT) are time-consuming or difficult due to software limitations. We evaluated the accuracy of simple renal measurements to estimate renal volume as compared with estimates made using specialized CT volumetric software.

METHODS

We reviewed 28 patients with contrast-enhanced abdominal CT. Using a standardized technique, one urologist and one urology resident independently measured renal length, lateral diameter and anterior-posterior diameter. Using the ellipsoid method, the products of the linear measurements were compared to 3D volume measurements made by a radiologist using specialized volumetric software.

RESULTS

LINEAR KIDNEY MEASUREMENTS WERE HIGHLY CONSISTENT BETWEEN THE UROLOGIST AND THE UROLOGY RESIDENT (INTRACLASS CORRELATION COEFFICIENTS: 0.97 for length, 0.96 for lateral diameter, and 0.90 for anterior-posterior diameter). Average renal volume was 170 (SD: 36) cm(3) using the ellipsoid method compared with 186 (SD 37) cm(3) using volumetric software, for a mean absolute bias of -15.2 (SD 15.0) cm(3) and a relative volume bias of -8.2% (p < 0.001). Thirty-one of 56 (55.3%) estimated volumes were within 10% of the 3D measured volume and 54 of 56 (96.4%) were within 30%.

CONCLUSION

Renal volume can be easily approximated from contrast-enhanced CT scans using the ellipsoid method. These findings may obviate the need for 3D volumetric software analysis in certain cases. Prospective validation is warranted.

Predictive preoperative factors for renal insufficiency in patients followed for more than 5 years after radical nephrectomy

Purpose

We assessed the predictive factors for renal insufficiency in patients followed for more than 5 years after radical nephrectomy.

Materials and Methods

Age, gender, history of diabetes, history of hypertension, body mass index, preoperative estimated glomerular filtration rate (eGFR), serum uric acid, urine albumin, normal renal parenchymal volume, tumor size, and ratio of normal parenchymal volume of the removed kidney to that of the remaining kidney were evaluated retrospectively in 89 patients who underwent radical nephrectomy from January 2001 to December 2005. Patients were included whose renal parenchymal volume was measurable by use of perioperative imaging (computed tomography or magnetic resonance imaging), whose preoperative eGFR was greater than 60 mL/min/1.73 m², and who were followed for more than 5 years. To measure renal parenchymal volume from imaging, we integrated the extent of the normal renal parenchyma from axial slides of images.

Results

In univariate and multivariate binary regression analysis, the parenchymal volume of the remnant kidney (p=0.001), a history of diabetes (p=0.035), and preoperative eGFR (p=0.011) were independent factors for renal insufficiency. By use of a receiver operating characteristic curve, a volume of 170 mL was determined to be an appropriate cutoff value, with sensitivity of 58.7% and specificity of 74.4% for the parenchymal volume of the remnant kidney for predicting eGFR less than 60 mL/min/1.73 m² (area under the curve, 0.678). The parenchymal volume of the remnant kidney was also an independent factor for the downgrading of the chronic kidney disease category in the multivariate linear regression analysis (p=0.021).

Conclusions

Preoperative eGFR, a history of diabetes, and the radiologic volume of the remaining kidney parenchyma could be useful factors for predicting postoperative renal function. Patients with parenchymal volumes of less than 170 mL have a higher risk of postoperative renal insufficiency, which should be considered carefully when choosing a treatment modality.

Renal volumetric analysis: a new paradigm in renal mass treatment assessment

Abstract Background and Purpose: Multiple renal volumetric assessment studies have correlated parenchymal volume with the glomerular filtration rate. The objective of this study was to compare renal volumes before and after treatment of renal masses with either partial nephrectomy or radiofrequency ablation (RFA).

PATIENTS AND METHODS

We reviewed our prospectively collected database of patients with renal masses who were treated between November 2001 and January 2011 with robot-assisted laparoscopic partial nephrectomy (RALPN), laparoscopic RFA (LRFA), or CT-guided percutaneous RFA (CTRFA). Digital Imaging and Communications in Medicine CT imaging data were analyzed in an open-source viewer. Volumetric calculations were used to measure the normal, enhancing bilateral renal parenchyma and tumor volumes. Normal parenchymal volume loss was compared among treatments.

RESULTS

There were 96 patients (68 men) with an average age of 68.0 (36-84) years who met our inclusion criteria. The average tumor diameter, tumor volume, and nephrometry score (NS) was 3.5 cm, 32.0 cm(3), and 7.1 in RALPN (n=26), 2.6 cm, 9.8 cm(3), and 7.1 in CTRFA (n=47), and 2.9 cm, 14.3 cm(3), and 7.2 in LRFA (n=23) groups. The percent change in the operated kidney volume was similar in RALPN (-12%±15), CTRFA (-13%±16), and LRFA (-17%±18) groups. NS was the only variable in a multivariate linear regression model that correlated with the amount of volume lost in the ipsilateral kidney.

CONCLUSIONS

Our retrospective volumetric analysis of renal parenchyma before and after partial nephrectomy or RFA of renal masses revealed that all treatments produce similar volume of collateral damage.