Transperitoneal Versus Retroperitoneal Robotic-Assisted Partial Nephrectomy in Patients with Obesity

Abstract

Introduction:

We aim to compare transperitoneal (TP) and retroperitoneal (RP) robotic partial nephrectomy (RPN) in obese patients. Obesity and RP fat can complicate RPN, especially in the RP approach where working space is limited.

Materials and Methods:

Using a multi-institutional database, we analyzed 468 obese patients undergoing RPN for a renal mass (86 [18.38%] RP, 382 [81.62%] TP). Obesity was defined as body mass index ≥30 kg/m²^*. A 1:1 propensity score matching was performed adjusting for age, previous abdominal surgery, tumor size, R.E.N.A.L nephrometry score, tumor location, surgical date, and participating centers. Baseline characteristics and perioperative and postoperative data were compared.

Results:

In the propensity score-matched cohort, 79 (50%) TP patients were matched with 79 (50%) RP patients. The RP group had more posterior tumors (67 [84.81%], RP versus 23 [29.11%], TP; P < .001), while the other baseline characteristics were comparable. Warm ischemia time (interquartile range; 15 [10, 12], RP versus 14 [10, 17] minutes, TP; P = .216), operative time (129 [116, 165], RP versus 130 [95, 180] minutes, TP; P = .687), estimated blood loss (50 [50, 100], RP versus 75 [50, 150] mL, TP; P = .129), length of stay (1 [1, 1], RP versus 1 [1, 2] day, TP; P = .319), and major complication rate (1 [1.27%], RP versus 3 [3.80%], TP; P = .620) were similar. No significant difference was observed in positive surgical margin rate and delta estimated glomerular filtration at follow-up.

Conclusion:

TP and RP RPN yielded similar perioperative and postoperative outcomes in obese patients. Obesity should not be a factor in determining optimal approach for RPN.

Introduction

Robotic partial nephrectomy (RPN) is the most common choice for the surgical management of localized renal masses, with increasing adoption in recent years.¹ RPN has been associated with many perioperative advantages compared with open and laparoscopic approaches, such as decreased length of hospital stay (LOS), less estimated blood loss (EBL), shorter warm ischemia time (WIT), and improved early renal functional preservation with comparable morbidity.^2–5

RPN is most often performed via the transperitoneal (TP) approach, which has the advantage of a larger working space, which allows for greater maneuverability of robotic instruments.⁶ In addition, TP was the first approach developed for RPN, maintaining good familiarity and comfortability for many robotic surgeons.⁶ However, the TP approach must traverse the peritoneal cavity, increasing risk of bowel injury and ileus due to bowel manipulation.⁷ Conversely, the retroperitoneal (RP) approach avoids abdominal structures, thus limiting mobilization of the colon. This makes for easy access to the kidney, an RP organ, by avoiding possible abdominal adhesions.⁷ This is of particular use for access and visualization of posterior kidney tumors, specifically behind the hilum, which can be difficult to access transperitoneally.⁷

Due to a more recent development and restricted workspace in the RP space, the RP approach has a steep learning curve and limited robotic instrument maneuverability, which may predispose to operative complications such as injury to the vena cava.^6,8

There is an abundance of literature that shows no differences in perioperative outcomes between the TP and RP approaches.^6,9–12 However, two more recent systematic reviews and meta-analyses showed that the RP approach had lower operating room (OR) time, LOS, and EBL, and rates of minor complications.^13,14

There is ample evidence that RPN is a safe procedure in obese patients—defined as body mass index (BMI) ≥30 kg/m²—with decreased rates of complications compared with an open approach, however, it remains a known fact that obesity is a risk factor for increased surgical complications generally.^15–18 Obesity has been associated with increased visceral fat.¹⁹ More visceral fat theoretically contributes to increased peritoneal and RP fat. For this reason, it may be postulated that certain surgical techniques involving these anatomical areas would be more challenging in obese patients. Studies have shown that intra-abdominal fat independently predicted perioperative complications and major complications after minimally invasive partial nephrectomy.^20,21 While RP RPN may generally be associated with fewer complications than TP RPN, increased RP fat in obese patients in theory may complicate RP RPN due to a more restricted workspace.²²

Few studies have focused on the safety of RP RPN in obese patients, and to the best of our knowledge, no study to date has directly compared surgical outcomes for RP RPN and TP RPN in obese patients.¹⁵ As a large and increasingly prevalent part of the patient population, this question is important.¹⁹ In this study, we sought to compare the perioperative and postoperative outcomes between TP and RP approaches in obese patients who underwent RPN for renal masses. We hypothesized that obese patients in the RP group would experience worse perioperative and postoperative outcomes than those in the TP group due to increased operative difficulty secondary to a more confined working space.

Materials and Methods

Data source and patient's selection

Data for this study were obtained from our institutional review board-approved multi-institutional database of patients who have undergone RPN in the United States using the multiport platform (n = 4681). The database is prospectively maintained and stored at the Icahn School of Medicine at Mount Sinai, New York. All patients, at least 18 years of age with obesity from the database were subsequently identified for study eligibility (n = 2008). To be further eligible for study inclusion, patients must have available data on the type of surgical approach utilized (n = 821).

To reduce the risk of selection bias, patients who had a solitary kidney (n = 26), prior ipsilateral surgery (n = 11), horseshoe kidneys (n = 3), metastatic disease (n = 2), end-stage kidney disease (n = 4), missing information on tumor location (n = 99), and multiple or bilateral tumors (n = 17) were excluded from the analysis. Also, missing data on previous abdominal surgery were also excluded from the analysis (n = 191). Overall, 468 patients were included in the study: TP (n = 382 [81.62%]) and RP (n = 86 [18.38%]).

Covariates

Baseline demographic, clinical, and tumor-specific characteristics included in the study are age, sex, BMI, American Society of Anesthesiologists (ASA) score, Charlson Comorbidity Index (CCI), baseline estimated glomerular filtration rate (eGFR), previous abdominal surgery, tumor size, R.E.N.A.L nephrometry score, and tumor location (anterior, posterior, or neither). eGFR was calculated using the CKD-EPI creatinine equation for glomerular filtration rate.^23,24

Outcomes

Perioperative and postoperative outcomes evaluated in this study include OR time, WIT, EBL, blood transfusion rate, rate of conversion to open surgery, rate of conversion to radical surgery, LOS, postoperative complication rates (any, major [Clavien–Dindo classification grade ≥3]), positive margin status, last follow-up eGFR, and delta eGFR. Delta eGFR was defined as the difference between the last follow-up eGFR and baseline eGFR.

Statistical analysis

Categorical variables were presented using frequencies and percentages, while continuous variables were presented as medians and interquartile ranges. To minimize confounding, we utilized a propensity score matching approach. A probit regression model adjusting for age, previous abdominal surgery, tumor size, R.E.N.A.L nephrometry score, tumor location, data of surgery, and the participating centers was used to estimate the propensity score. With the estimated propensity scores, TP and RP groups were matched in a 1:1 ratio using the nearest neighbor matching algorithm with a caliper of 0.2 of the standard deviation of the propensity score and without replacement. Balance was assessed using a standardized mean difference (SMD), and a SMD ≤0.10^* was considered a negligible imbalance. Baseline characteristics and perioperative and postoperative data were compared between both approaches using χ², Fisher exact tests, Mood's median test, and Mann–Whitney U test.

All analyses were conducted using STATA Version 14.1 (College Station, TX, USA), and statistical significance was determined at P < .05.

Results

Overall, 468 robotic-assisted partial nephrectomy (TP [n = 382 (81.62%)] versus RP [n = 86 (18.38%)]) patients with obesity were included in this study. Baseline demographic, clinical, and tumor-related characteristics for both groups are presented (Table 1). Compared with patients who had TP, those who had RP had similar median age (61 years [interquartile range (IQR): 50, 67] versus 59 years [IQR: 50, 67]; P = .138) and a similar proportion of males (65.71% versus 62.12%; P = .917). While tumor size (2.9 cm [IQR: 2.1, 4.0], TP versus 3.0 cm [IQR: 2.3, 3.6], RP; P = .623) and R.E.N.A.L nephrometry score (7 [IQR: 5, 9], TP versus 8 [IQR: 6, 9], RP; P = .052) were comparable between the two approaches, a significantly higher proportion of posterior tumors were managed using the RP approach (143 [37.43%], TP versus 71 [82.56%], RP; P < .001).

Table 1.

Baseline Characteristics Between Transperitoneal and Retroperitoneal Approaches Among Robotic-Assisted Partial Nephrectomy Patients with Obesity Before and After Propensity Score Matching

	Unmatched cohort			1:1 Propensity-matched cohort
	Transperitoneal	Retroperitoneal	P	Transperitoneal	Retroperitoneal	P
N	382 (81.62)	86 (18.38)		79 (50.00)	79 (50.00)
Age, years	61 (53, 68)	59 (50, 67)	.138	58 (50, 66)	59 (49, 67)	.753
Sex			.917			.739
Male	251 (65.71)	56 (65.12)		52 (65.82)	50 (63.29)
Female	131 (34.29)	30 (34.88)		27 (34.18)	29 (36.71)
BMI, kg/m²	33.93 (31.62, 37.49)	33.26 (31.56, 37.92)	.568	33.00 (31.31, 37.38)	33.13 (31.41, 37.76)	.993
ASA	3 (2, 3)	3 (2, 3)	.807	2 (2, 3)	3 (2, 3)	.472
CCI	3 (2, 5)	3 (2, 4)	.363	3 (2, 4)	3 (2, 4)	.682
Baseline eGFR	86.78 (68.29, 99.41)	91.16 (66.78, 102.91)	.219	91.20 (77.56, 101.59)	91.90 (69.34, 103.32)	.959
Previous abdominal surgery			.980			.750
No	196 (51.31)	44 (51.16)		42 (53.16)	40 (50.63)
Yes	186 (48.69)	42 (48.84)		37 (46.84)	39 (49.37)
Tumor size, cm	2.9 (2.1, 4.0)	3.0 (2.3, 3.6)	.623	3.1 (2.0, 4.5)	3.0 (2.3, 3.6)	.560
R.E.N.A.L Nephrometry score	7 (5, 9)	8 (6, 9)	.052	8 (6, 9)	8 (6, 9)	.831
Location			<.001			<.001
Anterior	119 (31.15)	5 (5.81)		25 (31.65)	5 (6.33)
Posterior	143 (37.43)	71 (82.56)		23 (29.11)	67 (84.81)
Neither	120 (31.41)	10 (11.63)		31 (39.24)	7 (8.86)

Bold value is significant at P < 0.05.

Continuous variable presented as median (interquartile range).

ASA, American Society of Anesthesiologist; BMI, body mass index; CCI, Charlson Comorbidity Index; eGFR, estimated glomerular filtration rate.

Other baseline characteristics were similar between the two groups.

In the propensity score-matched cohort, a total of 79 (50%) TP patients were matched with 79 (50%) RP patients. Similar to the unmatched cohort, a significantly higher proportion of posterior tumors (23 [29.11%], TP versus 67 [84.81%], RP; P < .001) were managed using the RP approach, while other baseline characteristics were comparable between the two approaches (Table 1).

Perioperative and postoperative outcomes in the propensity-matched cohort were compared and presented as well (Table 2). The RP approach had a comparable median WIT (15 [IQR: 11, 20] minutes, RP versus 14 [IQR: 10, 17] minutes, TP; P = .216), median OR time (129 [IQR: 116, 165] minutes, RP versus 130 [IQR: 95, 180] minutes, TP; P = .687), median EBL (50 [IQR: 50, 100] mL, RP versus 75 [50, 150] mL, TP; P = .129), blood transfusion rate (1 [1.27%], RP versus 1 [1.27%], TP; P = 1.000), rate of conversion to open surgery (0 [0.00%], RP versus 1 [1.27%], TP; P = 1.000), median LOS (1 [IQR: 1, 1] day, RP versus 1 [IQR: 1, 2] day, TP; P = .319), overall postoperative complication rate (4 [5.06%] RP versus 8 [10.13%], TP; P = .369), and major complication rate (1 [1.27%], RP versus 3 [3.80%], TP; P = .620).

Table 2.

Perioperative and Postoperative Outcomes Between Transperitoneal and Retroperitoneal Approaches Among Robotic-Assisted Partial Nephrectomy Patients with Obesity After Propensity Score Matching

	1:1 Propensity-matched cohort
	Transperitoneal, n (%)	Retroperitoneal, n (%)	P
Ischemia time, minutes^a	14 (10, 17)	15 (11, 20)	.216
OR time, minutes^a	130 (95, 180)	129 (116, 165)	.687
EBL, mL^a	75 (50, 150)	50 (50, 100)	.129
Blood transfusion	1 (1.27)	1 (1.27)	1.000
Conversion to open	0 (0.00)	1 (1.27)	1.000
Conversion to radical	5 (6.33)	3 (3.80)	.719
LOS, days^a	1 (1, 2)	1 (1, 1)	.319^b
PSM	2 (2.53)	4 (5.06)	.681
Postoperative complication
Overall	8 (10.13)	4 (5.06)	.369
Major (Clavien ≥3)	3 (3.80)	1 (1.27)	.620
Last eGFR^a	80.47 (60.21, 93.97)	74.27 (57.37, 90.29)	.453
Delta eGFR^a	−10.02 (−21.98, −1.05)	−11.29 (−21.39, −3.43)	.658

Continuous variable presented as median (interquartile range).

Mood's median test.

EBL, estimated blood loss; eGFR, estimated glomerular filtration rate; LOS, length of stay; OR, operating room; PSM, positive surgical margin.

Similarly, there was no significant difference in the positive surgical margin (PSM) rate (4 [5.06%] versus 2 [2.53%], P = .681). At median follow-up of 5 months (IQR: 1, 10), last eGFR and Delta eGFR were also similar between the TP and RP groups.

Discussion

In this retrospective multi-institutional cohort study, we found that the TP and RP approaches for RPN yielded similar perioperative and postoperative outcomes in obese patients after propensity score matching.

RPN has been shown to be safe in obese patients.^15,16,18 This specific patient population is continuing to increase in prevalence and obesity is an independent predictor of renal cancer mortality.^25–27 Obesity has also been shown to be associated with increased adherent perinephric or “toxic” fat, which itself has been associated with increased perioperative complications in minimally invasive partial nephrectomies in some studies.^28,29 However, this would not obviously favor the RP or TP approach, and we did not assess this in our study. Adherent perinephric fat remains a poorly understood and quantified risk factor that will be important to continue to learn more about in the future as we continue to optimize RPN.

Other studies have shown beneficial outcomes for the RP approach in reducing perioperative morbidity and rate of minor complications.^13,14 However, these studies included a heterogeneous group of patients of all BMI and were not specifically designed for only obese patients such as in our cohort.

In this study, median ischemia time was 14 and 15 minutes for the TP and RP groups, respectively. Median EBL was 50 and 75 mL for the TP and RP groups, respectively. Median OR time was about 130 minutes in both groups and LOS was 1 day in both the groups. Transfusion was required in just above 1% of patients in both groups. PSM rate was 2.53% and 4.06% in the TP and RP groups, respectively. Major complication rates were 3.8% and 1.27% in the TP and RP groups, respectively. At last follow-up, Delta eGFR was about −10 for both groups. These perioperative and postoperative outcomes are similar to prior series of RPN in obese patients.^15,16,18,30

To our knowledge, Malki et al.'s is the only other study to attempt to characterize outcomes specifically to RP RPN in obese patients.¹⁵ All 110 obese patients in their study underwent RP RPN. They reported a median OR time of 130 minutes, WIT of 22 minutes, EBL of 30 mL, and a transfusion rate of 1.8%. The PSM rate was 0.9%, major complication rate was 0.9%, and they did not quantify change in eGFR or compare outcomes with those who underwent TP RPN.

To our knowledge, no study has compared the RP and TP approaches in RPN in obese patients. In the RP approach for the obese population, the challenge of the RP nature of the approach may be exaggerated with abundant RP fat, which can lead to less maneuverability of robotic instruments and a smaller workspace.⁶ Consequently, we initially hypothesized that this approach would be associated with more perioperative and postoperative complications. However, our study confirmed comparable perioperative outcomes as well as rates of overall (10.13% TP versus 5.06%, RP, P = .369) and major (3.80% TP versus 1.27% RP, P = .620) complications.

We believe that the similarities in outcomes between the more demanding RP approach and the TP approach are partly influenced by two factors. First, surgeons were able to choose a surgical approach based on tumor characteristics. The results of this study clearly show that surgeons more often chose the RP approach for posterior tumors due to the ease of tumor access, which contributes to satisfactory outcomes for this challenging technique. Second, surgeons in this study had considerable experience and expertise, and this familiarity with the more technically challenging RP RPN likely contributed to the comparable outcomes between approaches. In addition, both before and after matching, the TP and RP groups had a similar proportion of patients with prior abdominal surgery. These surgeries often lead to abdominal adhesions, which may complicate TP surgery and theoretically increase complications.

However, the type of abdominal surgery, as well as the size and number of incisions, largely determines the extent of adhesions, and these nuances were not captured in our data.

Our study should be viewed within the scope of several limitations. First, as a retrospective cohort study, we are limited in the conclusions that we can draw regarding causality. Another limitation of the study is that the complication rate depends on surgeon skill and experience. Specifically, the RP approach is a more challenging discipline that often requires highly trained surgeons to perform.⁸ Therefore, our study may be underestimating the true complication rate of the RP group as the sample may be biased toward highly skilled surgeons who are comfortable with the RP approach. In addition, we did not assess the number of cases that were converted from RP to TP either due to a paucity of operative space or a breach of the peritoneal border. While this is a rare occurrence, it is a source of imprecision in the data.

The generalizability of this study to the community setting may be challenged as well, as all surgeries were performed at high-volume academic medical centers where surgeons and medical staff often have more training and experience than those in other contexts.

Conclusion

TP and RP approaches to RPN yielded similar perioperative outcomes in obese patients. These data can be reassuring for surgeons who opt to utilize an RP approach in obese patients based on patient and tumor characteristics.

Footnotes

Acknowledgment

The authors would like to thank the Menon Family Foundation for the support of the research of author J.M.R.

Authors' Contributions

K.E.O.: Conceptualization, methodology, software, formal analysis, and writing—original draft. J.M.R.: writing—original draft, writing—review and editing, methodology, and data retrieval. A.T.B.: Writing—review and editing. L.Z.: Writing—review and editing and data retrieval. I.S.: Data retrieval. B.U.: Writing—review and editing and data retrieval. J.L.: Data retrieval. I.T.J.: Methodology and writing, review, and editing. A.D.: Data retrieval. M.D.S.: Writing—review and editing and resources. S.C.: Writing—review and editing and resources. R.A.: Writing—review and editing and resources. D.D.E.: Writing—review and editing and resources. A.B.: Resources. A.K.H.: Resources and writing—review and editing. J.P.: Writing—review and editing and resources. A.M.: Resources. P.M.P.: Resources. O.Z.: Writing—review and editing. K.K.B.: Supervision, conceptualization, resources, and writing—review and editing.

Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

References

Tran

MGB

, Aben

KKH

, Werkhoven

, et al. Guideline adherence for the surgical treatment of T1 renal tumours correlates with hospital volume: an analysis from the British Association of Urological Surgeons Nephrectomy Audit. BJU Int, 2020; 125(1):73–81; doi: 10.1111/bju.14862

, Ma

, Wang

, et al. Laparoscopic vs robot-assisted partial nephrectomy for renal tumours of >4 cm: A propensity score-based analysis. BJU Int, 2018; 122(3):449–455; doi: 10.1111/bju.14386

, Zhao

, Xu

, et al. Comparison of transperitoneal and retroperitoneal robotic partial nephrectomy for patients with complete upper pole renal tumors. Front Oncol, 2022; 11:773345; doi: 10.3389/fonc.2021.773345

Benway

, Bhayani

, Rogers

, et al. Robot assisted partial nephrectomy versus laparoscopic partial nephrectomy for renal tumors: A multi-institutional analysis of perioperative outcomes. J Urol, 2009; 182(3):866–872; doi: 10.1016/j.juro.2009.05.037

Ghani

, Sukumar

, Sammon

, et al. Practice patterns and outcomes of open and minimally invasive partial nephrectomy since the introduction of robotic partial nephrectomy: Results from the nationwide inpatient sample. J Urol, 2014; 191(4):907–913; doi: 10.1016/j.juro.2013.10.099

Hughes-Hallett

, Patki

, Patel

, et al. Robot-assisted partial nephrectomy: A comparison of the transperitoneal and retroperitoneal approaches. J Endourol, 2013; 27(7):869–874; doi: 10.1089/end.2013.0023

Strauss

, Lee

, Maffucci

, et al. The future of “Retro” robotic partial nephrectomy. Transl Androl Urol, 2021; 10(5):2199–2208; doi: 10.21037/tau.2019.12.09

McAllister

, Bhayani

, Ong

, et al. Vena caval transection during retroperitoneoscopic nephrectomy: Report of the complication and review of the literature. J Urol, 2004; 172(1):183–185; doi: 10.1097/01.ju.0000132143.33340.51

Mittakanti

, Heulitt

, Li

, et al. Transperitoneal vs. retroperitoneal robotic partial nephrectomy: a matched-paired analysis. World J Urol, 2020; 38(5):1093–1099; doi: 10.1007/s00345-019-02903-7

10.

Correa

, Yankey

, Li

, et al. Renal hilar lesions: Biological implications for complex partial nephrectomy. Urology, 2019; 123:174–180; doi: 10.1016/j.urology.2018.08.044

11.

Arora

, Heulitt

, Menon

, et al. Retroperitoneal vs transperitoneal robot-assisted partial nephrectomy: Comparison in a multi-institutional setting. Urology, 2018; 120:131–137; doi: 10.1016/j.urology.2018.06.026

12.

Okhawere

, Rich

, Ucpinar

, et al. A comparison of outcomes between transperitoneal and retroperitoneal robotic assisted partial nephrectomy in patients with completely endophytic kidney tumors. Urol Oncol, 2023; 41(2):111.e1–111.e6; doi: 10.1016/j.urolonc.2022.11.023

13.

Pavan

, Derweesh

, Hampton

, et al. Retroperitoneal robotic partial nephrectomy: Systematic review and cumulative analysis of comparative outcomes. J Endourol, 2018; 32(7):591–596; doi: 10.1089/end.2018.0211

14.

Zhu

, Shao

, Guo

, et al. Comparison of outcomes between transperitoneal and retroperitoneal robotic partial nephrectomy: A meta-analysis based on comparative studies. Front Oncol, 2021; 10:592193; doi: 10.3389/fonc.2020.592193

15.

Malki

, Oakley

, Hussain

, et al. Retroperitoneal robot-assisted partial nephrectomy in obese patients. J Laparoendosc Adv Surg Tech, 2019; 29(8):1027–1032; doi: 10.1089/lap.2019.0273

16.

Malkoc

, Maurice

, Kara

, et al. Robot-assisted approach improves surgical outcomes in obese patients undergoing partial nephrectomy. BJU Int, 2017; 119(2):283–288; doi: 10.1111/bju.13675

17.

, Aikou

, Seto

. Obesity as a surgical risk factor. Ann Gastroenterol Surg, 2018; 2(1):13–21; doi: 10.1002/ags3.12049

18.

Abdullah

, Dalela

, Barod

, et al. Robotic partial nephrectomy for renal tumours in obese patients: Perioperative outcomes in a multi-institutional analysis. Can Urol Assoc J, 2015; 9(11–12):859; doi: 10.5489/cuaj.3197

19.

Tchernof

, Després

. Pathophysiology of human visceral obesity: An update. Physiol Rev, 2013; 93(1):359–404; doi: 10.1152/physrev.00033.2011

20.

Gorin

, Mullins

, Pierorazio

, et al. Increased intra-abdominal fat predicts perioperative complications following minimally invasive partial nephrectomy. Urology, 2013; 81(6):1225–1231; doi: 10.1016/j.urology.2012.12.053

21.

Nesbitt

, Sharma

. Visceral fat is associated with high-grade complications in patients undergoing minimally invasive partial nephrectomy for small renal masses. Curr Urol, 2021; 15(1):52–58; doi: 10.1097/CU9.0000000000000001

22.

Abaza

, Gerhard

, Martinez

. Feasibility of adopting retroperitoneal robotic partial nephrectomy after extensive transperitoneal experience. World J Urol, 2020; 38(5):1087–1092; doi: 10.1007/s00345-019-02935-z

23.

Levey

, Stevens

, Schmid

, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med, 2009; 150(9):604–612; doi: 10.7326/0003-4819-150-9-200905050-00006

24.

Kutikov

, Uzzo

. The R.E.N.A.L. nephrometry score: A comprehensive standardized system for quantitating renal tumor size, location and depth. J Urol, 2009; 182(3):844–853; doi: 10.1016/j.juro.2009.05.035

25.

King

, Pollack

, Li

, et al. Continued increase in incidence of renal cell carcinoma, especially in young patients and high grade disease: United States 2001 to 2010. J Urol, 2014; 191(6):1665–1670; doi: 10.1016/j.juro.2013.12.046

26.

Huang

, Leung

DKW

, Chan

EOT

, et al. A global trend analysis of kidney cancer incidence and mortality and their associations with smoking, alcohol consumption, and metabolic syndrome. Eur Urol Focus, 2022; 8(1):200–209; doi: 10.1016/j.euf.2020.12.020

27.

Liu

, Sun

, Hou

, et al. The association between BMI and kidney cancer risk: An updated dose-response meta-analysis in accordance with PRISMA guideline. Medicine (Baltimore), 2018; 97(44):e12860; doi: 10.1097/MD.0000000000012860

28.

Kocher

, Kunchala

, Reynolds

, et al. Adherent perinephric fat at minimally invasive partial nephrectomy is associated with adverse peri-operative outcomes and malignant renal histology. BJU Int, 2016; 117(4):636–641; doi: 10.1111/bju.13378

29.

Fang

, Li

, Zhang

, et al. Analysis of predictors of adherent perinephric fat and its impact on perioperative outcomes in laparoscopic partial nephrectomy: A retrospective case–control study. World J Surg Oncol, 2021; 19(1):319; doi: 10.1186/s12957-021-02429-6

30.

Naeem

, Petros

, Sukumar

, et al. Robot-assisted partial nephrectomy in obese patients. J Endourol, 2011; 25(1):101–105; doi: 10.1089/end.2010.0272