We retrospectively reviewed the records of 271 patients who underwent partial nephrectomy for renal masses at our institution from 1993 to 2007. This study was approved by the Institutional Review Board. Among these patients, 138 underwent partial nephrectomy via VAMS, 102 by open technique, and 31 by laparoscopic technique. The approach was based on the preference of the surgeons and patients. Two surgeons performed the VAMS technique, two different surgeons performed the open technique, and another surgeon performed the laparoscopic technique. Tumors were defined as exophytic if the tumor extended more than 60% off the surface of the kidney, endophytic if the tumor extended less than 40%, and mesophytic if the lesion extended between 40% and 60% off the surface of the kidney on CT. Hilar lesions were defined as those located within 5 mm of the renal hilar great vessels. The cases were compared with regard to clinical parameters, operative data, pathological parameters, oncological outcomes, and renal functional outcomes. Glomerular filtration rate (GFR) was measured by using the four-variable Modification of Diet in Renal Disease formula [GFR=186.3×Pcr^-1.154×age^-0.203×0.742 (if female)].4 After partial nephrectomy, specimens were examined for surgical margins, tumor size, and histological subtype, and the Fuhrman nuclear grade was determined. A positive surgical margin was defined as tumor cells present at the inked margin on pathological review. Follow-up care consisted of physical examination, laboratory evaluation, chest radiography, and abdominal computerized tomography. These procedures were performed semiannually for the first two years and annually thereafter. Complications were listed in a standardized format using the Clavien-Dindo classification of surgical complications.5

The technique used for VAMS partial nephrectomy was similar in all cases. A 6-cm to 7-cm transverse skin incision was made anteriorly from the costal margin corresponding to the level of the 10th rib. We obtained sufficient operative space around the kidney using a specially designed self-retaining retractor (Thompson Surgical Inc., Traverse, MI, USA) (Fig. 1A). The operative field was observed through the monitor or by direct vision. A laparoscopic retrieval sac (LapSac®, Sejong, Korea) was introduced through the minilaparotomy incision and placed around the kidney (Fig. 1B). Laparoscopic bulldog clamps were applied to the renal artery and vein (Fig. 1C). The blind end of the LapSac® was opened with scissors and packed with finely ground ice slush for renal parenchymal hypothermia (Fig. 1D). The tumor was excised using a surgical knife. Any openings in the collecting system and blood vessels were meticulously closed in a watertight manner with 4-0 Vicryl. Monosyn 1-0 sutures were used to approximate the remaining renal parenchyma.

The previously described transperitoneal laparoscopic technique was performed under warm ischemia conditions.6 The open technique was performed with the patient in a full-flank position via an anterior subcostal incision below the 11th rib. The renal artery was clamped using a bulldog clamp, and regional hypothermia was instituted or omitted at the surgeon's discretion.

Data are presented as number (percentage) or mean±standard deviation. Chi-square and analysis of variance tests were used to compare qualitative and quantitative variables, respectively. Disease-free and cancer-specific survival was calculated using life tables and the Kaplan-Meier method with log-rank test statistics. All p values were two-sided, and p<0.05 was considered statistically significant. All data analysis was processed using SPSS statistical software (Statistical Product and Services Solutions, version 12.0, SPSS Inc., Chicago, IL, USA).

The clinicopathological and operative data of 271 patients who underwent VAMS, open, and laparoscopic partial nephrectomy are listed in Table 1. The proportion of women was higher in the VAMS than in the other groups; however, no other statistically significant differences in baseline characteristics were found among the three groups. Among 271 patients, 18 patients (6.6%) had a single kidney at operation, and partial nephrectomy was performed by VAMS technique in 12 patients and by open technique in six patients. Among 18 patients, 16 patients previously underwent nephrectomy before partial nephrectomy; 11 (61.1%) for renal cell carcinoma, 4 (22.2%) for benign renal disease, and one (5.6%) for urothelial carcinoma. Two patients had a unilateral single kidney due to renal agenesis.

Table 1 shows the surgical and functional outcomes. No significant difference was found in estimated blood loss, tumor location, tumor characteristics, need for transfusion, complications, and tumor size. Ischemic time and operative time were shorter in the open group compared to the VAMS and laparoscopic groups. Length of stay was shorter in the VAMS than the open group, but was not statistically different from the laparoscopic group. The overall complication rate was 15.9%. The complication rate was similar among the VAMS, open, and laparoscopic groups. Complications were categorized as grade 1 (hematuria, n=1), grade 2 (transfusion, n=17; infection, n=1; and hematoma, n=1), grade 3 (embolization, n=2), and grade 4 (sepsis, n=1) in the VAMS group. In the open group, there were grade 2 (transfusion, n=13; infection, n=1; and hematoma, n=1), and grade 4 (acute myocardial infarct, n=1) complications. In the laparoscopic group, there were grade 2 (transfusion, n=2 and hematoma, n=1) and grade 3 (bowel injury, n=1) complications. There were no differences in operative time, ischemic time, blood loss, hospital length of stay, or postoperative renal function between the group of 12 patients who underwent VAMS technique and 6 patients who had the open technique with a single kidney (data not shown). Preoperative GFR was similar among the three groups. After a follow-up of 47.7±29.1 months, GFR did not differ among the three groups.

Table 2 compared characteristics of renal cell carcinoma and oncologic outcomes by operative method. The most common pathological stage among the three groups was pT1aN0M0. However, 12 patients (14.6%) had pT1b lesions, and 2 patients (2.4%) had metastatic lesions at partial nephrectomy in the VAMS group. Recurrences were found in all three groups, including 3 patients in the VAMS group (3.7%); 3 patients in the open group (4.0%); and 2 patients in the laparoscopic group (8.7%; p=0.397). Five-year disease-free survival rates were 94.8% in the VAMS group, 95.8% in the open group, and 90.3% in the laparoscopic group, according to Kaplan-Meier analysis with log-rank test (p=0.485) (Fig. 2). Five-year cancer-specific survival rates was 96.3% in the VAMS group, 98.6% in the open group, and 100% in the laparoscopic group, according to Kaplan-Meier analysis using the log-rank test (p=0.452).