More than 60% of renal cell carcinomas are now detected incidentally. Such tumors are smaller than those found based on symptomatology, less likely to metastasize, and often amenable to nephron-sparing surgery (J Urol. 2004;172:2167-2171).
Over the past 10 years, partial nephrectomy has emerged as the gold standard for treatment of small renal masses, with equivalent oncologic outcomes, better preservation of renal function, and improved overall survival when compared with radical nephrectomy in selected patients (Mayo Clin Proc. 2000;75:1236-1242). Nevertheless, nephron-sparing surgery remains underutilized in this country, with radical nephrectomy being performed for more than 80% of renal tumors nationwide (J Urol. 2006;175[3 Pt 1]:853-857).
Cancer-specific outcomes are comparable and overall survival is superior in similar cohorts undergoing partial nephrectomy compared with radical nephrectomy for tumors 4 cm in diameter or less and even 7 cm or less (Mayo Clin Proc. 2000, and J Urol. 2008;179:468-471).
The improvement in survival in patients undergoing partial nephrectomy has been attributed to the lesser effect of nephron-sparing surgery on postoperative renal function, although this remains somewhat controversial (J Urol. 2008; 179:468-471). When compared with radical nephrectomy, partial nephrectomy better preserves renal parenchyma and function.
We evaluated independent factors predicting functional outcomes in 1,169 patients undergoing partial nephrectomy with median preoperative, nadir, and ultimate postoperative eGFRs of 77, 57, and 71, respectively (J Urol. 2008;180:2363-2369).
Baseline CKD was the major predictor of postoperative eGFR: In patients with a preoperative eGFR of 60 or more (normal preoperative renal function), eGFR 30-59 (stage 3 CKD), and eGFR 15-29 (stage 4 CKD), the incidence of postoperative acute kidney injury was 0.8%, 6.2%, or 34% and the incidence of chronic end-stage renal disease was 0.1%, 3.7%, or 36%, respectively.
Temporary or permanent loss of renal function occurred infrequently after partial nephrectomy. Immediate loss of function is a predictor of long-term renal function, which remains relatively stable after recovery from the initial postoperative insult.
Among surgical factors affecting nadir and ultimate eGFR, the duration of ischemia during partial nephrectomy is the greatest modifiable risk factor and efforts to limit ischemic time and injury should be pursued in both open and laparoscopic partial nephrectomy. Other factors leading to lower glomerular filtration following partial nephrectomy included solitary kidney, older age, gender, and tumor size.
Contemporary urologic management must focus on optimizing renal function, avoiding CKD, and minimizing the degree of CKD whenever possible. CKD is much more common than previously appreciated and has profound implications: It is now established as an independent, dose-dependent predictor of morbid cardiac events and overall mortality.
Creatinine-based estimates of GFR, such as the MDRD study formula, are strongly preferred when assessing renal function. Early referral for CKD should be considered, as nephrologic surveillance and intervention can delay progression toward renal failure, and any incremental improvement in renal function can yield tangible dividends.
The improved functional outcomes after nephron-sparing surgery, compared with nephrectomy, emphasize the importance of these approaches within the armamentarium of the practicing urologist.
The authors are affiliated with the Section of Urologic Oncology, Glickman Urological & Kidney Institute, Cleveland Clinic. Dr. Lane is a fellow in urologic oncology and Dr. Campbell is professor of surgery and residency program director.