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Annals of Surgical Oncology 9:680-687 (2002)
© 2002 Society of Surgical Oncology

ORIGINAL ARTICLES

Partial Nephrectomy: The Rationale for Expanding the Indications

Paul Russo, MD, Manlio Goetzl, MD, Rachel Simmons, MD, Jared Katz, MD, Robert Motzer, MD and Victor Reuter, MD

From the Departments of Urology (PR, MG, RS, JK), Medicine (RM), and Pathology (VR), Memorial Sloan-Kettering Cancer Center, New York, New York.

Correspondence: Address correspondence and reprint requests to: Paul Russo, MD, Department of Urology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave., New York, NY 10021; Fax: 212-717-3175; E-mail: russop{at}mskcc.org


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Background: We report preliminary results of partial nephrectomy for renal tumors of >=4 cm in 39 patients with the intent of extending the indications for kidney-sparing surgery.

Methods: From July 1989 to October 2001, 39 patients underwent a partial nephrectomy for renal cortical tumors >4 cm in maximum diameter. Fourteen (36%) had the procedure performed for essential reasons, and 25 (64%) had an elective kidney-sparing operation. We evaluated tumor location and histology, perioperative renal function, and postoperative complications.

Results: There were 20 conventional clear-cell (51%), 13 papillary (33%), 4 chromophobe (10%), and 3 oncocytomas (8%) with a median tumor size of 5 cm. After a median follow-up of 13 months, 36 patients had no evidence of disease, 1 patient had died as a result of other causes, and 2 patients who had essential operations were alive with disease. Twenty-three patients (70%) maintained normal postoperative renal function. Of six patients with moderate preoperative renal dysfunction, five (83%) had no change in postoperative renal function and only one patient required short-term dialysis.

Conclusions: With careful patient selection, partial nephrectomy can be effectively used to treat patients with renal cortical tumors >4 cm in diameter. The benefits of this approach include the effective local tumor control while at the same time preserving maximum renal function.

Key Words: Partial nephrectomy • Kidney-sparing surgery • Renal tumors • Tumor staging


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
At our center, several factors simultaneously affect the surgical management of localized renal cortical tumors: (1) a stage and tumor size migration secondary to earlier incidental detection, 1,2 (2) an enhanced appreciation of the different tumor histological subtypes and their varying metastatic potential,3 and (3) important recent reports indicating that patients subjected to radical nephrectomy are at increased risk of developing renal insufficiency as compared with matched patients treated with partial nephrectomy.4,5 These factors motivated us to review our contemporary experience with kidney-sparing operations for renal tumors of >4 cm in diameter. These operations were performed in patients for elective indications, e.g., normal contralateral kidney, or for essential indications, e.g., tumor in a functionally or anatomically solitary kidney. Our objective in this study was to determine the clinical, pathologic, and perioperative characteristics of these patients and assess surgical outcome.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
From July 1989 to October 2001, 1189 patients observed prospectively in a renal cancer surgical database underwent 1228 nephrectomies for renal cortical tumors at Memorial Sloan-Kettering Cancer Center.1,6–11 Of these operations, 279 (23%) were partial nephrectomies, 41 (3% of all nephrectomies) of which were performed in patients for tumors of >=4 cm. Excluded from consideration in this study was 1 patient with documented metastatic disease at the time of nephrectomy and 1 patient with tumor in a horseshoe kidney, leaving 39 patients available for our analysis. Demographic features analyzed included age, sex, method of presentation (incidental or symptomatic), maximum tumor diameter, the location of the tumor in the kidney, and any evidence of tumor multifocality. Pre- and postoperative renal function, operative renal ischemic time, and perioperative complications were also recorded. Survival time from the date of operation and current patient status were determined.

Partial nephrectomy was performed with an extraperitoneal flank approach, with mannitol (12.5 g/200 ml) given before renal arterial occlusion to limit ischemic injury to the kidney. Ice slush was regularly used to provide renal hypothermia for 15 minutes before tumor resection and kidney reconstruction.12,13 Tumor resection routinely included a surrounding rim of normal-appearing renal parenchyma and a frozen section of the deep surgical margin. Argon beam coagulation was applied to the renal cortex within the resection bed to provide additional hemostasis. In no case was tumor enucleation performed. In selected patients with underlying renal insufficiency and tumor in a solitary kidney, extensive partial nephrectomy was performed without renal arterial cross-clamping by using manual compression of the kidney to provide hemostasis and avoid certain postoperative acute tubular necrosis. The pathologist recorded tumor size (largest dimension), tumor histology, and surgical margin status. Tumor histological subtype was assigned by using the Heidelberg classification of renal cortical tumors, which describes the following neoplasms as malignant: conventional clear-cell, papillary, chromophobe, collecting duct, medullary, and unclassified carcinoma.3,14,15 Oncocytomas, although rarely metastatic, are considered to be in the family of renal cortical tumors.16 In certain multifocal tumor cases, pathologists found more than one histological subtype. Pathologic tumor staging was determined according to the most recent (1997) American Joint Committee on Cancer tumor-node-metastasis staging system:

  1. T1, <=7.0 cm in greatest dimension and limited to the kidney.
  2. T2, >7.0 cm in greatest dimension and limited to the kidney.
  3. T3a, tumor invades the adrenal gland or perinephric tissues but does not extend beyond Gerota’s fascia.
  4. T3b, extension into the renal vein or vena cava below the diaphragm.17

After surgery, patients were monitored at least every 6 months with a physical examination, chest radiograph, and serum creatinine measurement. Abdominal computerized tomography (CT) was performed yearly. The survival rate was calculated from the date of the operation to the date of the last follow-up evaluation.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
A total of 39 patients underwent partial nephrectomy for a renal cortical tumor of >4 cm in diameter. The group consisted of 29 (74%) men and 10 (26%) women, with a median age of 65 years (range, 37–83 years; Table 1). The median follow-up was 13 months (range, 1–138 months). Fourteen (36%) patients underwent operation for essential indications and 25 (64%) for elective indications. Of the 14 essential-operation patients, 9 had bilateral renal tumors, with 8 presenting synchronously and 1 presenting asynchronously (7 years later). Five other patients were considered as needing essential operations because of decreased renal function (n = 3) and tumor in a solitary kidney (n = 2).


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  		TABLE 1. Patient demographics and presentation
 
Ten (26%) patients presented with local symptoms, including three with gross hematuria, five with flank pain, one with a palpable flank mass, and one with both flank pain and gross hematuria. Twenty-eight (72%) had tumors that were incidentally discovered during abdominal imaging for other nonurological abdominal complaints or during follow-up evaluation (n = 6) for other malignancies, including endometrial cancer (n = 1), breast cancer (n = 2), and prostate cancer (n = 3).

The median tumor size was 5.0 cm (range, 4.1–10.0 cm), 5.3 cm (range, 4.1–10.0 cm) for the essential-operation patients, and 5.0 cm (range, 4.1–6.0 cm) for the elective-operation patients. Tumors were located in the polar aspects of the kidney in 26 cases (67%) and in the interpolar aspects of the kidney in 10 cases (26%); in 2 multifocal cases, tumors were found in different poles (5%), and in 1 case (3%) tumor location was not documented at the time of operation (Fig. 1). Histological subtypes were conventional clear-cell in 19 cases (49%), papillary renal cancer in 11 cases (28%), chromophobe in 4 cases (10%), oncocytoma in 2 cases (5%), multilocular cystic renal-cell in 1 case (3%), and mixed histology in 2 cases (5%). Thirty patients (77%) were P1, three (8%) were P2, five (13%) were P3a, and one (3%) was P3b (Table 2).



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  		FIG. 1. Tumor sizes and locations for patients treated with elective and essential partial nephrectomy.

 

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  		TABLE 2. Tumor pathology and staging
 
In 32 of 37 operations, renal arterial cross-clamping and ice slush hypothermia were used during the tumor resection. The median cold ischemic time was 37 minutes (range, 12–90 minutes). In four essential-operation cases and one elective-operation case, the operating surgeon did not cross-clamp the renal artery, to avoid a significant postoperative acute tubular necrosis. In these cases, compressing the renal parenchyma during the tumor resection provided hemostasis. The median renal ischemia time was 35 minutes (range, 12–66 minutes) in the elective-operation group and 41 minutes (range, 28–90 minutes) in the essential-operation group (P < .05).

Four patients (three essential-operation patients and one elective-operation patient) in the cohort (10%) had positive surgical margins on final pathology after partial nephrectomy. Of these four patients, three had chromophobe and one had conventional clear-cell histological subtypes. After a follow-up of 130, 20, 4, and 67 months, none of the patients developed a local recurrence. The single essential-operation patient, now with local kidney recurrence and distant lung metastases, had resected multifocal clear-cell carcinoma (tumor sizes: 9.0, 3.1, and 2.0 cm) 10 months after contralateral radical nephrectomy for a conventional clear-cell carcinoma. His recurrent disease was detected during routine follow-up CT scanning 41 months after his initial radical nephrectomy, at which time his serum creatinine was 2.3 mg/dl. An additional essential-operation patient was diagnosed with pulmonary metastases to the lungs 3 months after presenting at the time of the initial nephrectomy with lung nodules suggestive of disease.

Serum creatinine levels were available for all patients to assess pre- and postoperative renal function (Table 3). Thirty-three patients (9 essential and 24 elective procedures) had a normal preoperative serum creatinine level (.6–1.4 mg/dl). Of these 33 patients, 23 (3 essential, 20 elective) had normal postoperative serum creatinine levels, 9 patients (5 essential, 4 elective) had mild to moderate renal impairment after surgery (1.5–2.5 mg/dl), and 1 essential-operation patient had significant renal impairment at last follow-up (>2.5 mg/dl). Six patients (five essential, one elective) had mild to moderate renal impairment before surgery. Of these six patients, five (four essential and one elective) had mild to moderate renal impairment after surgery, and one essential-operation patient had high renal impairment. One essential-operation patient required temporary dialysis.


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  		TABLE 3. Serum creatine levels pre- and postoperatively recorded to assess renal function
 
There were no perioperative deaths. One patient died as a result of other causes (metastatic colon cancer). Twelve (31%; six elective and six essential procedures) patients had postoperative complications, including two patients with major complications—an elective-operation patient developed postoperative atrial fibrillation and experienced a pulmonary embolism, and a second essential patient had a cerebrovascular accident. Minor complications occurred in 10 patients (wound infection [n = 2], ileus [n = 2], atelectasis [n = 2], hallucinations, acute gouty attack, pneumonia, and bronchospasm).


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Strategies for the surgical management of renal cortical tumors are evolving largely because of three distinct factors: (1) the increasing incidence of incidentally detected, small, low-stage renal tumors because of improvements in abdominal imaging modalities; (2) the appreciation of the fact that renal cortical tumors represent a family of neoplasms with distinct histological, cytogenetic, and clinicopathologic features; and (3) the fact that patients undergoing radical nephrectomy experience detectable renal insufficiency when compared with matched patients treated with kidney-sparing operations.

Renal masses are currently being detected at an increased rate because of the widespread availability and improved precision of abdominal ultrasound, magnetic resonance imaging, and CT.18–20 These imaging studies are routinely ordered by clinicians for cancer patients during follow-up evaluations to assess nonspecific abdominal complaints, to screen for cancer, and to assist in determining the extent of disease in patients with known cancer.1,2,6 Approximately 90% of such solid renal masses represent renal cortical tumors,7 and, in a contemporary cohort of patients treated at our center, 65% had their renal cortical tumor discovered incidentally.1,2 For the cohort of patients with tumors of <=4 cm, 79% of patients were also diagnosed with tumors incidentally.1 Improvements in abdominal imaging have contributed to significant tumor stage and size migration over the last decade, with the median tumor size at presentation at our center now being approximately 4 cm in diameter.1 The earlier, incidental detection of renal cortical tumors has dramatically increased the pool of smaller kidney tumors presenting to the operating surgeon and allows the surgeon more therapeutic choices. Over the last decade, the urological community has accepted partial nephrectomy as a safe and effective alternative to radical nephrectomy, particularly for tumors of <=4 cm for patients with an anatomically or functionally solitary kidney (essential partial nephrectomy) or with a normally functioning contralateral kidney (elective or kidney-sparing partial nephrectomy).2,21–23 Although the 4-cm tumor size is generally accepted in the urological literature as a safe surgical boundary for elective partial nephrectomy, this limit does not have a biological basis, particularly when one considers the varying prognoses based on histological subtype. In addition, the recent change in the International Union against Cancer staging system to make T1 <7 cm (before 1997, it was <2.5 cm)17 suggests that there is a greater surgical comfort level for urological surgeons considering a partial nephrectomy for a tumor >4 cm. In this data set, 72% of patients presented with incidental renal tumors.

For many years, clinicians and pathologists alike have viewed solid renal masses as a single clinical entity broadly termed "hypernephroma" or "renal-cell carcinoma." Little attempt was made to organize the observed histological variants of renal cortical tumor or to gauge the potential effect of these variants on clinical outcome. After two decades of basic pathologic and clinical research, our former one-dimensional view of renal cortical tumors has been replaced with the new understanding that renal cortical tumors are, in fact, a family of neoplasms with distinct cytogenetic defects and histopathologic features. Modern imaging studies do not distinguish renal cortical tumors by histological subtype. The distinct histological subtypes are observed in both sporadic and the less common familial or hereditary tumor syndromes, such as von Hippel–Lindau disease (conventional clear-cell), hereditary papillary renal-cell carcinoma, familial renal oncocytoma, and the most recently described Birt-Hogg-Dube syndrome.24–30 The nonconventional sporadic renal cortical tumors (papillary, chromophobe, and oncocytoma), which account for approximately 35% of the total cases seen at our center, have a far more indolent or even benign natural history associated with a much reduced or absent metastatic potential, even though tumors can reach a large size.11 Overall survival for clinically localized renal cortical tumors now ranges from 75% to 100%, depending on the histological subtype, mode of presentation, pathologic stage, and tumor size.11 At our center, a postoperative prognostic nomogram for renal-cell carcinoma was designed that incorporates the following variables to provide a prognosis: mode of presentation, histological subtype, tumor size, and pathologic stage. The most significant predictors in combination were tumor size and histological subtype.11 If we include the 2 patients with multifocal renal-cell carcinoma with multiple histological subtypes (1 patient with 4.9-cm oncocytoma and .9-cm papillary tumors and 1 patient with a 9-cm conventional clear-cell tumor and 3.1- and 2-cm papillary tumors), the most potentially dangerous histologic subtype, conventional clear-cell carcinoma, was present in 20 (51%) patients (10 elective and 10 essential), including patients with multiple histological subtypes, followed by the more indolent papillary renal-cell carcinoma in 13 (33%) patients (11 elective and 2 essential), chromophobe in 4 (10%) patients (2 elective and 2 essential), and the virtually benign oncocytoma in 3 (8%) patients (2 elective and 1 essential). To date, one essential-operation patient has lung metastases, and another has local kidney recurrence and lung metastases, both arising from conventional clear-cell carcinoma.

The combination of incidental tumor detection coupled with the understanding that 35% of patients have renal tumors with minimal or no metastatic potential raises concerns that radical nephrectomy, whether by traditional open surgical techniques or emerging minimally invasive techniques, may be surgical overtreatment. A recent report from the Mayo Clinic also suggests that patients who undergo radical nephrectomy may develop signs of renal function deterioration. This group reviewed a 30-year experience with partial and radical nephrectomy for renal tumors and, using a matched-pair analysis, reported a decreased risk for the development of proteinuria (34.5% vs. 55.2%) and a decreased risk for developing a serum creatinine level of >2 mg/dl (11.6% vs. 22.4%) for patients undergoing an elective partial nephrectomy as opposed to a radical nephrectomy.5 In their study, there was no difference in cancer-specific survival between the patients treated with partial or radical nephrectomy. Although their data did not reveal a difference in the rate of dialysis between the patients treated by radical or partial nephrectomy, this difference may not yet be apparent, because 90% of the patients in this report underwent surgery in the last 10 years. Because renal tumor patients are also subject to comorbid conditions, such as hypertension, peripheral vascular disease, and diabetes, a greater rate of chronic renal insufficiency and eventual dialysis would be expected in the radical nephrectomy group. Our own group at Memorial Sloan-Kettering Cancer Center has confirmed this observation in a data set of 290 patients with small renal tumors treated with radical nephrectomy (n = 173) and partial nephrectomy (n = 117). Patients were controlled for diabetes, cigarette smoking, American Society of Anesthesiologists score, and hypertension. Patients undergoing a radical nephrectomy had a mean postoperative serum creatinine level of 1.5 mg/dl, as opposed to 1.0 mg/dl for partial nephrectomy (P = .008).5 These two studies stand in contradistinction to what many urological surgeons have been trained to believe and what was derived from the renal donor transplant literature—that overall renal function is preserved for patients as long as one normally functioning kidney remains. However, the donor population is not directly comparable because the median age of the donor is 37.5 years and the median age of the renal tumor nephrectomy patient is 61.7 years.31 Although most studies show that renal function in donors remains stable for many years after renal donation,32 some patients do develop proteinuria, hypertension, and decreased creatinine clearance after the nephrectomy.33,34 The added potential effect of comorbid medical conditions such as diabetes and hypertension plus the 25-year age differential all likely contribute to the above-described observations by Lau et al.4 and McKiernan et al.5 relative to proteinuria and increasing serum creatinine in patients undergoing radical nephrectomy.

In this series, one of the essential-operation patients required short-term dialysis, and two essential-operation patients developed severe renal impairment (creatinine >2.5 mg/dl). Of the patients who underwent elective partial nephrectomy, 24 patients had normal preoperative serum creatinine, and 20 (83%) had normal serum creatinine at last follow-up. Four patients in this group developed moderate renal impairment (creatinine .5–2.5 ng/dl). The single elective-operation patient with moderate preoperative renal impairment had unchanged postoperative renal function. Of the nine essential-operation patients with normal preoperative serum creatinine, three remained stable after surgery, five developed moderate renal impairment, and one developed severe renal impairment. Of the five essential-operation patients with moderate preoperative renal impairment, four remained stable after surgery, with continued moderate renal impairment, and one developed severe renal impairment.

In this series, the renal cortical tumor in 26 (67%) of the 39 cases was located in polar locations of the kidney, often with exophytic extensions into the perinephric fat. In such cases, we perform polar nephrectomy and leave ample surrounding perinephric fat with the resected specimen. Often-voiced contraindications to partial nephrectomy, such as proximity to the collecting system or a major venous or arterial branch, have not proved to be serious impediments to partial nephrectomy in our experience, as long as adequate reconstruction can be performed and a clear surgical margin can be achieved. Despite the technical challenge created by extending the limits of kidney-sparing surgery to include tumors of >4 cm, our complication rate of 31% is comparable to that of the published literature. Campbell et al.35 reported that 1 or more complications occurred after 78 (30%) of 259 partial nephrectomies, and Duque et al.36 reported complications in 27% of 66 patients, also after partial nephrectomies.

Improvements in laparoscopic surgical techniques have ushered in new enthusiasm for a minimally invasive approach for donor nephrectomy, the removal of nonfunctional kidneys, and the resection of kidney tumors.37–39 Surgical investigators must now incorporate the above-described reports into their clinical decision-making algorithms when deciding whether to perform a minimally invasive total nephrectomy or an open partial nephrectomy. The learning curve is currently steep as these same investigators apply minimally invasive surgical techniques to the more complicated partial nephrectomy. Serious concerns exist that more total nephrectomies will be performed by minimally invasive or laparoscopic techniques in patients otherwise perfectly suitable for partial nephrectomy to promote the short-term dividends of reduced analgesia and convalescence time. The long-term risks of chronic renal insufficiency or dialysis, both associated with total nephrectomy and, ultimately, the potential for far more morbidity and cost, have not to date been stressed in the recent literature and need to be discussed with patients during operative planning, particularly if the index renal cortical tumor is small and associated with an excellent long-term prognosis.40

A commonly voiced criticism regarding partial nephrectomy is that the potential for recurrent disease within the kidney (from 1% to 6%) is a dangerous occurrence and that radical nephrectomy would eliminate that future concern.41 Morgan and Zincke42 reported a local recurrence rate of 6% in 104 patients, and Herr43 reported a 1.4% local recurrence rate in a 10-year follow-up of 70 patients. Local recurrence may be due to incomplete tumor resection, to the surgeon’s not noticing a satellite tumor, or to the emergence over time of a clinically detectable tumor from a microscopic tumor. At Memorial Sloan-Kettering Cancer Center, we attempt to minimize the risk of a local tumor recurrence during kidney-sparing surgery by removing all of the fat on the kidney surface and carefully inspecting its surface. In addition, we routinely use intraoperative ultrasound to search for satellite subcortical renal tumors that could potentially escape preoperative radiological imaging or intraoperative inspection.44 Detecting a satellite lesion, some of which can be millimeters in diameter and possess histological features similar to those of the larger, more clinically obvious, tumors, should prompt its complete excision and not be a contraindication to proceeding with kidney-sparing surgery. For patients with hereditary or familial renal tumor syndromes, who often require multiple and repeated partial nephrectomies over time, the combination of careful intraoperative visual inspection of the surface of the kidney and intraoperative ultrasound has been effective in providing local tumor control, maintaining native kidney function, and avoiding or delaying dialysis.45 All partial nephrectomy patients will remain under close postoperative surveillance. Should a significant tumor recurrence be detected, repeat exploration and resection by partial or radical nephrectomy could be advocated. The approach to familial and hereditary renal cancers effectively used at centers such as the National Cancer Institute combines careful radiological surveillance and partial nephrectomy. Tumor growth is monitored until its size is operable but still has low metastatic potential (3.5–4.0 cm), at which point partial nephrectomy is performed. Every effort is made to keep such patients off dialysis for as long as possible.46 For patients with nonfamilial forms of renal cortical tumor, we would not expect tumor recurrence to be a common event but would use similar strategies as applied to the familial and hereditary forms of renal cortical tumor. In this series, four patients had positive surgical margins on final pathologic section (three essential, one elective; three chromophobes, one conventional) and, despite a limited follow-up (130, 67, 20, and 4 months), none of the patients has developed a detectable local recurrence or metastatic disease. It is not known whether intraoperative surgical methods, such as argon beam laser of the resection bed, provide any added therapeutic margin. All patients, including those with close or positive surgical margin, require surveillance for local recurrence. Intraoperative frozen section should be performed liberally to avoid a positive surgical margin. The weight of the clinical evidence to date is that the histological subtype associated with metastatic disease in 90% of cases is the conventional clear-cell type, suggesting that a close surgical margin or local recurrence of a nonconventional histology renal cortical tumor would not carry an ominous prognosis for either local recurrence or eventual metastatic disease.

Another strong incentive to consider extending the limits of partial nephrectomy is the small but real risk of bilateral renal tumor development. Bilateral nonfamilial or nonhereditary renal cortical tumors are generally reported to occur in approximately 4% of sporadic renal cortical tumor patients.2 The histological and clinical features of sporadic renal cortical tumors closely follow those of sporadic unilateral renal cortical tumors.8 Although the majority of bilateral renal cortical tumors occur synchronously, the asynchronous disease-free interval may be measured in years and, rarely, decades. It is obvious that partial nephrectomy is integral in managing such patients, whether they present synchronously or asynchronously, and the possibility that late recurrence (or new tumor formation) could occur needs to be factored in when planning surgical interventions. As the above-described stage migration continues, anticipated survival from the index initial tumor will be longer, particularly if the patient has an indolent or benign histological tumor subtype. Exposure to a potential asynchronous, contralateral tumor may then become a late clinical challenge. Facing that challenge with a solitary kidney is a greater clinical problem than in a patient whose index tumor was treated initially with a kidney-sparing partial nephrectomy. In this series, eight (21%) patients had bilateral synchronous renal cortical tumors, and one patient (3%) had asynchronous bilateral renal-cell carcinoma. This disproportionately large number of patients with bilateral renal cortical tumors reflects referral patterns at our center and a selection bias for patients with tumors >=4 cm treated with partial nephrectomy.

In conclusion, we think that the current studies of renal cortical tumors have provided significant incentive to consider extending the limits of kidney-sparing surgery. Although our experience with 39 such patients is preliminary and limited by a median follow-up of 13 months, the clinical, pathologic, and surgical features of these patients suggest that extension of the kidney-sparing surgical strategies to include larger T1 tumors has a place in the surgical management of renal cortical tumors. In our study, nearly three quarters of the tumors were detected incidentally, and the most lethal histological subtype, conventional clear-cell, comprised only 51% of the patients; 59% of the patients had tumors that were in polar locations. Only one essential-operation patient required short-term dialysis. Two patients developed metastatic disease: an essential-operation patient with a history of large bilateral renal conventional clear-cell tumors had recurrent disease, with both metastatic and local recurrence, and one essential-operation patient with suspicious lung nodules at presentation later was definitively postoperatively diagnosed with lung metastases. The overall complication rate in this series was 31%. When the increased knowledge of renal cortical tumor biology and new concerns for the long-term renal function of the patient are combined with the tumor size and stage migration, there exists ample rationale to extend the limits of kidney-sparing surgery. This surgical strategy to localized kidney tumors deserves careful study and long-term follow-up.


   Acknowledgments
 
The authors thank Brenna Nichols for expert editorial assistance.


   Footnotes
 
Of the 39 patients who underwent partial nephrectomy for renal cortical tumors of >=4 cm and who were observed for a median of 13 months, 36 patients were free of disease, 70% retained normal preoperative renal function, and only 51% had the most aggressive tumor histological subtype—conventional clear-cell carcinoma. The rationale for extending the limits of kidney-sparing surgery on the basis of the biologic diversity of renal cortical tumors, as well as concerns for long-term renal function, is presented.

Received for publication December 26, 2001. Accepted for publication April 16, 2002.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

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