Retroperitoneal Laparoscopic Partial Nephrectomy Versus Radical Nephrectomy for Clinical T1 Renal Hilar Tumor: Comparison of Perioperative Characteristics and Short-Term Functional and Oncologic Outcomes

Abstract

Purpose:

To present our single-center experience with retroperitoneal laparoscopic partial nephrectomy (LPN) and retroperitoneal laparoscopic radical nephrectomy (LRN) for T1 renal hilar tumors and evaluate which one is better.

Methods:

A retrospective review of 63 patients with hilar tumors undergoing retroperitoneal LPN or LRN was performed. The perioperative characteristics, change in estimated glomerular filtration rate (eGFR) from baseline to month 3, and oncologic outcomes were summarized.

Results:

In total, 25 patients underwent LPN, and 38 patients underwent LRN. The mean tumor size in the LPN and LRN groups was 4.5 and 4.9 cm, respectively. The mean operation time was longer in the LPN group than that in the LRN group (212.5 minutes versus 160.7 minutes, respectively; P < .05). Patients undergoing the LPN had a longer median length of hospital stay after surgery (9 days versus 7 days, P < .05). Four percent of patients in the LPN group experienced postoperative complications compared with 5% of patients in the LRN group, which was not significantly different. Compared with preoperative eGFR, postoperative eGFR at 3 months decreased by 15.2 mL/min/1.73 m² and 27.8 mL/min/1.73 m² in the LPN and the LRN groups, respectively (P < .05). There was one local recurrence in the LPN group and three local or distant recurrences in the LRN group (P > .05).

Conclusions:

In experienced hands, although retroperitoneal LRN can result in shorter operation times and shorter lengths of stay, retroperitoneal LPN can preserve renal function better than LRN. Retroperitoneal LPN should be the priority in selected patients with T1 renal hilar tumors, especially for patients with renal insufficiency.

Introduction

Renal hilar tumor is defined as lesion being located in the hilum region and having direct physical contact with the renal artery and/or the renal vein. This can be confirmed by preoperative imaging and intraoperative observations.¹ Previously, most patients with hilar tumors underwent open surgery or laparoscopic radical nephrectomy (LRN) due to tumors' special location and complexity. Thanks to technical and conceptual advances, Gill et al.² first utilized laparoscopic partial nephrectomy (LPN) in the treatment of renal hilar tumors. Since then many reports showed that LPN can be a feasible technique for hilar tumors.^1,3,4 Nevertheless, it is controversial whether partial nephrectomy is more beneficial for hilar tumors. To our knowledge, there is no report about a comparison between LPN and LRN in the treatment of renal hilar tumors. We aim to present our initial experience with 63 patients by comparing perioperative characteristics and short-term functional and oncologic outcomes and evaluate which surgery is optimal for hilar tumors.

Materials and Methods

Patients and grouping

A retrospective review was performed on a total of 63 patients with renal hilar tumors(< = 7 cm) carried out by a single surgeon (Dr. Tie Chong) at our hospital from May 2014 to May 2017. These patients underwent either LPN or LRN, and no clinical features were absolute contraindications to the LPN for renal hilar tumors, with the patients' understanding that conversion to LRN would be performed if LPN was not technically possible. Hence, we gathered the clinical data of 25 patients undergoing LPN and 38 patients undergoing LRN.

Data collection

Preoperative parameters, including age, gender, affected kidney(left/right), American Society of Anesthesiologists physical status classification, body mass index, tumor size, estimated glomerular filtration rate (eGFR), and RENAL nephrometry score,⁵ were collected. The Modification of Diet in Renal Disease (MDRD) study equation was used to measure the eGFR. According to RENAL nephrometry score, these patients were classified in low complexity group, intermediate complexity group, and high complexity group, scoring 4–6, 7–9, and 10–12, respectively.

In surgery, operative time, estimated blood loss, transfusion rate, and conversion to radical nephrectomy were recorded.

Postoperative outcomes included postoperative hospital length of stay, histopathology, margin status, complication, eGFR at postoperative 3 months, and local or distant recurrence rate. Complications were classified using the Clavien-Dindo system.⁶

Surgical techniques

Retroperitoneal LPN

After general anesthesia, the patient was placed in a healthy lateral decubitus position with overextension. Retroperitoneal cavity and three lumbar Trocar ports were made following standard steps as Xu et al. described.⁷ After the retroperitoneal cavity was established, the pararenal fat was separated from the Gerota's fascia. The kidney would be rotated 180° around the renal pedicle. Based on this, tumor excision and kidney suture could be performed smoothly. By careful dissection, the renal vessels were freed, and the proximal renal artery away from tumor was clamped with the bulldog clamps to prevent bleeding. Then cold scissors were used to separate the tumor from the normal kidney tissue, meanwhile, leaving a kidney defect on the resection bed. Two-layer suturing was the most important part in the surgery and managed as follows: a deep layer at the resection bed and another superficial layer at the renal capsule were sutured continuously with the application of 2-0 Vicryl and 1-0 Vicryl, respectively. Every suture was ended with Hem-o-lok clip. After this, the bulldog clamp was removed, and hemostasis was estimated. A specimen bag was used to take out the specimen.

Retroperitoneal LRN

Anesthesia, surgical position, retroperitoneal cavity creation, and trocar insertion were completed as above. The surgical steps were followed as reported by Wang et al.⁸

Statistical analysis

The SPSS 20.0 (Statistical Package for Social Science) as a statistic software was used for data analysis. Categorical variables are showed in the form of numbers and percentages, and the Pearson χ² test was used to compare these variables. As for continuous variables, they were presented with mean or median and range. The Shapiro–Wilk normality test was used to test the assumptions of normality for all continuous variables. The Student t test was used for normally distributed variables, and the Wilcoxon rank sum test was used for non-normally distributed variables.

Results

A total of 63 patients with hilar tumors underwent retroperitoneal surgery, of which 25 underwent LPN, and 38 underwent LRN (Table 1). The mean age was lower for the LPN group compared with the LRN group (55.0 years versus 60.6 years); however, this was not significantly different. In total, 56% and 53% of patients in the LPN group and LRN group, respectively, were male. And 68% of tumors in the LPN group and 50% in the LRN group were located in right kidney. The mean ASA score was 1.9 and 1.8, respectively. The mean BMI was 23.2 and 23.9 kg/m², respectively. Preoperative eGFR was a little higher in the LPN group than it in the LRN group (103.4 mL/min/1.73 m² versus 93.0 mL/min/1.73 m², respectively; P > .05).

Table 1.

Patient Characteristics ^*

Variable	LPN (n = 25)	LRN (n = 38)	P value
Mean age, y (range)	55.0 (32–76)	60.6 (41–86)	.078
Gender			.793
Male, n (%)	14 (56)	20 (53)
Female, n (%)	11 (44)	18 (47)
Tumor affected kidney			.158
Left, n (%)	8 (32)	19 (50)
Right, n (%)	17 (68)	19 (50)
Mean ASA score (range)	1.9 (1–3)	1.8 (1–3)	.486
Mean BMI (range)	23.2 (17.2–28.3)	23.9 (18.3–35.2)	.367
Mean preoperative eGFR (range)	103.4 (66.4–164.5)	93.0 (46.2–140.2)	.064

n = 63.

ASA, American Society of Anesthesiologists; BMI, body mass index; eGFR, estimated glomerular filtration rate.

All tumors were single, and the maximum tumor diameter ranged from 2.4 to 7 cm. The mean tumor size was 4.5 cm in the LPN group and 4.9 cm in the LRN group (Table 2). All the tumors were confirmed as T1 N0 M0 according to the American Joint Committee on Cancer Tumor Node Metastasis (AJCC TNM) staging. The difference of histologic type between two groups was not statistically significant. The hilar tumors were divided into low complexity, moderate complexity, and high complexity groups through RENAL nephrometry scoring, and distribution of different complexity was comparable between the groups and is showed in Table 2. There was no statistical difference in RENAL nephrometry scoring.

Table 2.

Tumor Characteristics ^*

	LPN (n = 25)	LRN (n = 38)	P value
Mean tumor size, cm (range)	4.5 (2.6–6)	4.9 (2.4–7)	.202
Histology, n (%)			.114
Clear cell RCC	20 (80)	36 (94)
Papillary RCC	0	1 (3)
Chromophobe RCC	1 (4)	0
Other	4 (16)	1 (3)
pT stage, n (%)			.700
pT1a	7 (28)	9 (24)
pT1b	18 (72)	29 (76)
RENAL nephrometry scoring, n (%)			.734
Low complexity, score 4–6	1 (4)	1 (3)
Moderate complexity, score 7–9	12 (48)	15 (39)
High complexity, score 10–12	12 (48)	22 (58)

n = 63.

RCC, renal cell carcinoma; RENAL (radius, exophytic/endophytic properties of the tumor, nearness of tumor deepest portion to the collecting system or sinus, anterior/posterior descriptor, and the location relative to polar lines).

There was a longer mean operation time in the LPN group than it in the LRN group (212.5 minutes versus 160.7 minutes, respectively; P < .05; Table 3). The median estimated blood loss was 100 mL for both groups. Patients had a longer median length of hospital stay after surgery in the LPN group compared with patients in the LRN group (9 days versus 7 days, respectively; P < .05). There was no patient needing blood transfusion despite hemorrhage. No positive margin occurred in both groups. Four percent of patients in the LPN group had postoperative complications compared with 5% of patients in the LRN group. In the LPN group, the one case with urine leakage (Clavien grade IIIa) was relieved after temporary Double-J stent implantation and percutaneous drainage. In the LRN group, there were two patients experiencing complications (Clavien grade II), of which one patient was systematic thrombocytopenia without clear etiology requiring platelet transfusion after surgery, and the other one was wound infection which needed antibiotics. In the surgery, two conversions occurred from partial nephrectomy to radical nephrectomy for the safety. Compared with preoperative eGFR, eGFR at postoperative 3 months decreased by 15.2 mL/min/1.73 m² and 27.8 mL/min/1.73 m² in the LPN and LRN groups, respectively. This difference was statistically significant. During the short-term follow-up, there was one and three local or distant recurrences in the LPN and LRN groups, respectively.

Table 3.

Comparison of Perioperative Characteristics and Short-Term Functional and Oncological Outcomes

Results	LPN (n = 25)	LRN (n = 38)	P value
Mean operative time, min (range)	212.5 (105–405)	160.7 (65–305)	.002
Median estimated blood loss, mL (range)	100 (0–600)	100 (0–500)	.221
Median length of stay, d (range)	9 (6–20)	7 (3–13)	<.001
Transfusion, n (%)	0	0	1.000
Positive margin, n (%)	0	0	1.000
Postoperative complications, n (%)	1 (4)	2 (5)	1.000
Surgery conversion, n (%)
To radical nephrectomy	2 (8)	NA
Mean ΔeGFR 3 month, (range)	−15.2 (−71.6 to 11.8)	−27.8 (−59.7 to 9.1)	.001
Local or distant recurrence, n (%)	1 (4)	3 (8)	1.000

ΔeGFR 3 mo, change from baseline to month 3; Bold-face P values are statistically significant.

NA, not applicable.

Discussion

A multicenter review showed that there was no difference in the rate of cancer-specific deaths between 1454 patients who underwent PN or RN for T1 tumors.⁹ Furthermore, nephron-sparing surgery (NSS) was associated with a better preservation of renal function.¹⁰ Theoretically, the LPN could get similar benefits for clinical T1 renal hilar tumor. By now there is a lack of consensus which is a better surgery for the treatment of clinical T1 renal hilar tumors, although the use of NSS gradually increased. When comparing the laparoscopic approaches, we prefer the retroperitoneal approach for hilar tumors since Chinese people have lower BMI, yet European and American laparoscopic experts tend to use the transperitoneal approach for providing a larger surgical space.¹¹ Xu et al.⁷ reported that the retroperitoneal LPN can easily get access to the posterior hilar structures and the posterolateral surface of the kidney, and it can also reduce the risk of intra-abdominal organ injury. In addition, a meta-analysis summarized that retroperitoneal LPN had a shorter operation time than transperitoneal LPN.¹²

Retroperitoneal LPN is a challenging surgery for renal hilar tumors, even in experienced hands. Specific tumor locations can increase the difficulty of renorrhaphy after tumor resection, which can lead to a longer operation time; moreover, renorrhaphy has a close relationship with hemostasis and complications because of nearness to the renal vessels and collecting system. In our experience, the bulldog clamp should be placed in a proximal renal artery to minimize the disruption of resection and renorrhaphy. Of course, surgeons should do their best to preserve the normal kidney tissue for reconstruction as much as possible on the premise of complete resection and perform two-layer suturing to minimize postoperative complication. Zhang et al.¹³ shared their ring suture techniques in retroperitoneal LPN for hilar tumors and it can also acquire a favorable outcome without postoperative hemorrhage, urine leakage, hematuria, or renal atrophy. Xu et al.⁷ reported that only 2 of 14 cases occurred perirenal fluid collection and recovered with active surveillance. In our study, only one of 25 cases (4%) had complication in the LPN group, and two of 38 cases (5%) had complication in the LRN group, but it is not significantly different. Hence, retroperitoneal LPN and LRN can acquire similar complication rate in the treatment of renal hilar tumors.

Renal function preservation is an important parameter that we should focus on. We compared postoperative eGFR with preoperative eGFR. Kang et al.¹⁴ reported that operation method (LRN or LPN) was a significant factor to predict postoperative renal function. Besides, they found that the renal function can recover slightly after LPN and LRN and remain constant after 3 months. Based on this finding, we chose 3 months as time point to evaluate the renal function change. In our study, change in eGFR from baseline to month 3 had a decrease of 15% and 30% in the LPN and LRN groups, respectively. The LPN is an effective method to preserve the renal function.

Compared with partial nephrectomy, radical nephrectomy is able to establish a safer margin, especially for the renal hilar tumors. George et al.¹⁵ reported that 43 patients with hilar tumors underwent the LPN, and one (2.3%) had positive surgical margin, which showed that the LPN is a feasible surgical technique for hilar tumors. In our cohort study, there was no positive surgical margin. We believe this result is related to surgeon's advanced laparoscopic techniques. In experienced hands, renal hilar tumor can also acquire a satisfactory margin result. Of course, negative surgical margin status does not ensure a negative recurrence, and we still need a long-term follow-up to evaluate the oncologic control. Only 1 recurrence of 25 cases (4%) observed at mean follow-up of 10.5 months (3–27) in the LPN group was compared with three recurrences of 38 cases (8%) at mean 18.1 months (3–40) in the LRN group and that was not statistically significant. This short-term oncologic outcome demonstrates that both LPN and LRN can be effective procedures for renal hilar tumors.

Although partial nephrectomy is an alternative to radical nephrectomy for T1 renal tumors, many patients remained to undergo the latter.¹⁶ Similarly, the patients with T1 renal hilar tumors also need a careful planning. At our institute, a preoperative discussion is conducted with patients to explain the benefits and risks of the LPN and LRN, and we keep a low threshold for conversion from partial nephrectomy to radical surgery. In our study, there were two cases converted from the LPN to the LRN to ensure the safety.

The greatest limitation of our study is that this review is retrospective, and potential biases do exist. In this study, we tried our best to keep potential biases to a minimum. Known characteristics which are also potential confounding factors like age and gender are compared between two groups. As the analysis suggests, no statistically significant difference between two groups was found. In other words, given information collected, we didn't find statistical evidence in favor of any bias. In contrast, although no clinical features were absolute contraindications to the LPN for renal hilar tumors, it was hard to determine who should undergo LPN or LRN. At last, we and patients chose a surgery option together. With that being said, there's no consistent selection bias known to the doctor in the process of treatment assignment. To prevent the inherent bias, prospective random control test should be a best way to solve this problem in the future, and frequency matching should be used to decrease the difference between patients in the LPN group and the LRN group. Since the sample size is small, this may result in negative statistical findings. For the accuracy of assessment, we need a larger number of cases and a longer follow-up.

Conclusion

Our single-center experience demonstrates that retroperitoneal LRN can get shorter operation time and shorter length of stay, but retroperitoneal LPN can preserve renal function better than can LRN in experienced hands. Retroperitoneal LPN should be considered a better way for T1 renal hilar tumors, especially for patients with renal insufficiency.

Footnotes

Acknowledgments

The authors thank all the patients and their family members for their cooperation, and they also thank Ashley Di Meo for correcting the language.

Disclosure Statement

No competing financial interests exist.

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