Introduction

Radical nephrectomy has been the standard treatment for kidney cancer for decades since Robson et al. [1] introduced it as a treatment for renal cell carcinoma. Since then, partial nephrectomy, which is more nephron-sparing than radical nephrectomy, for small kidney tumors has been actively debated and considered non-inferior to radical nephrectomy in surgical outcomes, including overall survival and cancer-specific survival [2,3]. Although partial nephrectomy is mainly performed for clinical T1 tumors, it is also performed for clinical T2 tumors and has been increasingly performed for small kidney tumors because of the advantage of nephron preservation [4-6]. The surgical technique of partial nephrectomy has evolved in recent decades from open partial nephrectomy to laparoscopic and robotic partial nephrectomy [7,8].

Partial nephrectomy can be divided into the peritoneal or retroperitoneal approach [9]. The peritoneal approach has traditionally been practiced more than the retroperitoneal approach because of a wider surgical space and more familiar anatomical landmarks. Conversely, while the retroperitoneal approach has a narrower surgical space, it allows direct access to the renal artery, and intraperitoneal organs such as the intestine, spleen, and liver can be avoided. Therefore, there is less pressure on intraperitoneal organ injury with the retroperitoneal approach, which is beneficial for restoring bowel function after surgery [10,11].

We conducted a retrospective study to compare transperitoneal robotic partial nephrectomy (TRPN) and retroperitoneal robotic partial nephrectomy (RRPN) performed by a single surgeon at our institution to investigate potential differences in tumor characteristics and surgical outcomes between the two procedures.

Methods

Ethical statements: This study was approved by the Institutional Review Board of Kosin University Gospel Hospital (IRB No. KUGH 2023-06-026) and was conducted in accordance with the recent Declaration of Helsinki. Informed consent was waived by the board.

We performed a retrospective evaluation using the electronic medical records of patients who underwent robotic partial nephrectomy from November 2019, when RRPN was first performed in our hospital, to May 2022. RRPN was performed by a single urologist (SHK).

We reviewed demographic and perioperative data, such as age, hospital stay, operation time (skin-to-skin), warm ischemic time (WIT), estimated blood loss (EBL) during surgery, positive surgical margin (PSM), tumor size, RENAL Nephrometry Score (RNS), tumor location, preoperative and postoperative estimated glomerular filtration rate (eGFR), and complications. Hospital stay was defined as the number of resource days from the day of surgery to the day of discharge. RNS was obtained with the method introduced by Kutikov and Uzzo in 2009 [12]. Complications were classified according to the Clavien-Dindo classification system [13]. Tumor location was assessed using computed tomography or magnetic resonance imaging and classified as upper/lower/unassessable and medial/lateral/unassessable. Preoperative eGFR was assessed within 1 month before surgery, and postoperative eGFR was assessed within 1 week before discharge. To assess postoperative eGFR change, we defined eGFR change as the postoperative eGFR value minus the preoperative value.

Statistical analysis was conducted with IBM SPSS. Mann-Whitney U test was used for quantitative variables, and the chi-square test for categorical variables. A significant p-value was determined as less than 0.05.

Results

Seventy robotic partial nephrectomies (35 TRPN and 35 RRPN) were performed. All surgeries were carried out using the da Vinci Xi system (Intuitive Surgical).

The median hospital stays after surgery (both TRPN and RRPN) was 8.38 days, operation time 148 minutes, WIT 27.26 minutes, EBL 278 mL, tumor size 2.37 cm, RNS score 5.89, eGFR change (postoperative eGFR–preoperative eGFR) –1.11. The two groups had statistically significant differences in operation time, EBL, tumor size, and RNS. However, no significant difference in age, length of hospital stays, WIT, PSM rate, eGFR changes, and complication rates was detected between the groups. Larger tumors were noted in the TRPN group, and the RNS was higher. In contrast, the operation time was shorter and EBL was lower in the RRPN group. In the RRPN group, the tumor tended to be significantly more posterior and lower, but the PSM and complication rates were not significantly different (Table 1).

There were two cases of PSM in the TRPN group and two cases in the RRPN group, but only one case of clear cell renal cell carcinoma in the TRPN group was confirmed as an angiomyolipoma by histopathological examination. There were no Clavien-Dindo grade 3 or higher complications in the TRPN group and three cases (urine leakage at the surgical site) in the RRPN group. Ureteral stenting or percutaneous nephrostomy was performed for the three cases.

Discussion

TRPN requires more dissection than RRPN, particularly when the tumor is located in the posterior portion. This difference in dissection may result in a shorter operation time (128±39 minutes vs. 169±51 minutes, p<0.001) and less EBL (136±164 mL vs. 420±641 mL, p=0.015) for RRPN. However, if the tumor is located in the anterior or superior portion, using the RRPN approach is difficult. This is why a significantly higher proportion of tumors in the posterior or inferior segments was noted in the RRPN group compared to the TRPN group. In addition, the narrower surgical space in RRPN compared to TRPN tended to favor smaller tumors (2.77±1.54 cm vs. 1.96±0.91 cm, p=0.01). The results of our study are similar to those of other studies. Choi et al. [14] compared TRPN and RRPN conducted by a single surgeon. According to these authors, although there was no significant difference in tumor complexity or location between the two groups, the RRPN group had better results in terms of operation time (273 minutes vs. 244 minutes, p<0.001), WIT (21 minutes vs. 19 minutes, p=0.008), and EBL (150 mL vs. 100 mL, p=0.003). In Harke et al.’s multicenter analysis [15], the RRPN group had a shorter median operation time than the TRPN group after propensity score matching (139 minutes vs. 119 minutes, p<0.001), which included tumor characteristics and shorter hospitalization (9 days vs. 8 days, p<0.001). Zhou et al.'s meta-analysis of 21 studies [16] also showed significant benefits of RRPN in terms of operation time, length of hospitalization, and EBL. Although the studies had some variations, overall, RRPN outperformed TRPN in operative time and EBL. The RRPN group displayed a shorter operation time, consistent with prior research [14-16]. However, tumor size and RNS were greater in the TRPN group in our study. Thus, caution must be exercised when interpreting these results, as these variables may affect operation time. The EBL was also higher in the TRPN group, similar to other studies [14-16]. This finding could also be attributed to tumor complexity, such as tumor size and RNS.

Our study has some limitations. The study was a retrospective analysis, and patients were divided into two groups based on the surgical method used in their case. The decision regarding surgical method was influenced by the size and location of the tumor, which led to variations in tumor size, tumor complexity as measured by RNS, and tumor location between the groups. Conducting a retrospective comparison of the two surgical methods under similar conditions is infeasible because of the impact of tumor size and location on the choice of surgical procedure. A large-scale randomized prospective study in which tumor size or location is matched between the study groups would elucidate the advantages and disadvantages of the two surgical techniques based on tumor location and complexity.

In our study, RRPN had advantages over TRPN in terms of operation time and EBL. RRPN is usually performed for renal masses in the posterior or lower portions. However, there is a tendency to perform TRPN rather than RRPN for tumors that are more complex in terms of size or RNS. Although the choice between RRPN and TRPN depends on the surgeon's preference, RRPN seems effective for treating small kidney tumors if selected appropriately.

Article information

Conflicts of interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Author contributions

Conceptualization: YS, SHK, TSK. Data curation: YS. Formal analysis: YS. Investigation: YS, SHK, TSK, DHK, SBK. Methodology: YS, SHK, TSK. Project administration: SHK. Resources: YS, SHK. Supervision: SHK, TSK. Visualization: YS. Writing - original draft: YS, SHK. Writing - review & editing: YS, SHK, TSK, DHK, SBK. Approval of final manuscript: all authors.

References

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Figure & Data

References

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