More recently, nephron sparing has become increasingly used, as it has been shown to maintain oncologic equipoise with more radical surgery, in properly selected patients, while allowing the preservation of more normal nephron mass. Other studies have suggested that there is a higher incidence of renal insufficiency following radical nephrectomy when compared with partial nephrectomy for T1a tumors. Here, Sorbellini and colleagues out of Memorial Sloan Kettering describe a prognostic nomogram that may facilitate patient counseling with regards to anticipated renal function following extirpative renal surgery.

At their institution over a 14 year period, 161 partial nephrectomies and 857 radical nephrectomies were performed. For the purposes of this study, renal insufficiency was defined as 2 serum creatinine levels > 2.0mg/dl at least one month post-operatively. Patients in this study had a median follow-up of 21.2 months. The authors calculated preoperative and postoperative kidney volumes using the ellipsoid formula, V=L1 X L2 X L3 X /66, where V represents volume and L represents length, and then calculated the percentage change in renal volume for the nomogram. In this series, a total of 111 patients (10.9%) experienced renal insufficiency of whom 105 (12.3%) had radical nephrectomy and 6 (3.7%) underwent partial nephrectomy (p=0.005). The authors then examined preoperative creatinine, ASA score, % change in renal volume, age, and sex as variables predictive of 7 year freedom from renal insufficiency. In multivariate analysis, all but ASA score were found to be associated with freedom from renal insufficiency after nephrectomy, although ultimately, ASA score was included in the final nomogram. After boot strapping and internal validation, the concordance index for the nomogram was found to be 0.835.

This study provides the clinician a potential tool to counsel patients regarding the likelihood of developing renal insufficiency up to 7 years out from renal surgery. As the editorial comments associated with the article point out, it is derived from a highly selected cohort and was not externally validated. Further, it is not a preoperative nomogram in that post-operative renal volume is part of the assessment, and one can argue telling the patient his risk at that point is not of real benefit in making decisions regarding surgical interventions.

Maximiliano Sorbellinia, Michael W. Kattanc, Mark E. Snydera, A. Ari Hakimia, Debra M. Sarasohnb and Paul Russo

J Urology. 2006 August;176(2):472-476

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Renal Cancer Section

Written by Christopher G. Wood, MD, a Contributing Editor with UroToday.

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