Recent Advances and New Perspectives in Surgery of Renal Cell Carcinoma

Abstract

Renal cell carcinoma (RCC) is one of the most common types of cancer in the urogenital system. For localized renal cell carcinoma, nephron-sparing surgery (NSS) is becoming the optimal choice because of its advantage in preserving renal function. Traditionally, partial nephrectomy is performed with renal pedicle clamping to decrease blood loss. Furthermore, both renal pedicle clamping and the subsequent warm renal ischemia time affect renal function and increase the risk of postoperative renal failure. More recently, there has also been increasing interest in creating surgical methods to meet the requirements of nephron preservation and shorten the renal warm ischemia time including assisted or unassisted zero-ischemia surgery. As artificial intelligence increasingly integrates with surgery, the three-dimensional visualization technology of renal vasculature is applied in the NSS to guide surgeons. In addition, the renal carcinoma complexity scoring system is also constantly updated to guide clinicians in the selection of appropriate treatments for patients individually. In this article, we provide an overview of recent advances and new perspectives in NSS.

1. Introduction

With the development of screening techniques, increasing numbers of renal tumors are being diagnosed at an early stage without clinical symptoms [1]. Surgical resection remains the cornerstone of renal cell carcinoma (RCC) treatment [2]. Recent studies have shown that renal sparing techniques, such as partial nephrectomy (PN), achieve a comparable tumor prognosis and significantly improve perioperative morbidity and mortality. And guidelines from multiple urological associations recommend PN as the standard of care for early renal cell carcinoma [3, 4]. With the development of laparoscopic nephron-sparing surgery (NSS), urological surgeons strive to shorten the renal warm ischemia time (WIT) and preserve more renal parenchyma while removing tumor tissue. In order to preserve more renal parenchyma, laparoscopic renal tumor enucleation and renorrhaphy technique including deepsutures running the base of the defect, precise vesselsuture ligation, and no renorrhaphy at all have been developed [4]. In order to shorten the renal warm ischemia time, there are some surgical methods, such as microwave ablation/radio frequency ablation/laser/hydro-jet-assisted zero-ischemia laparoscopic partial nephrectomy (LPN), selective renal artery occlusion/embolization-assisted zero-ischemia laparoscopic partial nephrectomy, unassisted zero-ischemia laparoscopic partial nephrectomy and zero-ischemia laparoscopic renal tumor enucleation, and zero-ischemia laparoscopic partial nephrectomy by re-suturing [5]. Preoperative three-dimensional visualization technology of renal vasculature is increasingly used to implement multiple zero-ischemic approaches in laparoscopic nephron-sparing surgery [6].

The Mayo Clinic thrombus classification is widely used to describe levels of inferior vena cava tumor thrombus and is significant to guide the operation for renal cell carcinoma with venous thrombus in the open era [7]. But in the minimally invasive surgery era, Prof. Zhang et al. summarized a large number of surgical experiences of renal cell carcinoma with venous thrombus and put forward the “301 classification” system [8]. The system based on anatomical landmarks in which one grade corresponds to one surgical strategy improves surgical choice in the treatment of renal cell carcinoma with venous thrombus.

In this article, we summarize the various new surgical methods for renal cell carcinoma and describe the advantages and disadvantages of each of these methods. Moreover, we provide an overview of the latest research on RCC surgery and new scoring system which would help physicians to better personalize surgical treatment for patients.

2. Introduction of assisted zero-ischemia surgery

With increasing evidence indicates warm ischemia time (WIT) can have significant impact to minimize the loss of renal function after partial nephrectomy (PN), scientists are committed to reducing warm ischemia time, even achieving zero-ischemia surgery. Techniques trying to achieve zero ischemia are as follows.

2.1 Selective renal artery embolization technique

2.1.1 Methods

DSA superselective target artery embolization was performed in the interventional operating room 1 to 12 hours before surgery. Seldinger puncture method was used to insert F5 arterial catheter through the right femoral artery, and Yashiro catheter was used to perform renal artery angiography, superselected to the renal tumor supply artery, injected embolic agent, and then angiography was performed again to understand the embolization effect. Then laparoscopic partial nephrectomy with zero ischemia was performed [9].

2.1.2 Results

At 3-month and 1-year follow-up, the median increase of serum creatinine levels was 0.3 mg/dL and 0.24 mg/dL, respectively, and the median decrease of split renal function was 9% and 5%, respectively. The median tumor size was 4.2 cm (range, 2.5 to 6.5 cm). The median operative time was 62 minutes (35–220 minutes), the median blood loss was 150 ml (20–800 ml), and the median hospital stay was 3 days (2–12 days). None of the patients had end-stage CKD [10].

2.1.3 Complications

Complications are urinary tract infection, pulmonary infection, postoperative incision infection, postoperative intestinal obstruction, pelvic effusion and lower extremity venous thrombosis, as well as complications after superselective arterial embolization (low back pain, fever, infection, local hematoma), etc.

2.1.4 Advantages and limitations

With this technique, bleeding can be effectively stopped during surgery and the survival of the remnant kidney tissue can be maximized. The disadvantages of this technique are as follows. Firstly, superselective artery embolization is not successful in about 20% of cases, which is negatively correlated with the RENAL score. Especially in the face of large and endogenous tumors, the use of DSA to superselectively embolize the tumor to supply the artery needs more theoretical support [10]. Secondly, superselective arterial embolization can lead to edema and gangrene in the area of hand surgery, which brings difficulty to correctly distinguish normal tissue from tumor tissue. It is necessary to be vigilant all the time; otherwise, the tumor is easy to rupture and the positive rate of surgical margin will increase. For beginners, adequate surgical margin should be ensured from the tumor body. Thirdly, the use of iodine contrast and hemostatic agents could lead to contrast medium-induced nephropathy [11].

2.2 Selective renal artery occlusion technique

2.2.1 Methods

Nohara T and colleagues first introduced the concept of this technique in 2008 as a modified form of anatrophic partial nephrectomy [12]. First, the feeding branch of the tumor was determined by angiographic assessment or computed tomography angiography (CTA). During the operation, secondary or even tertiary renal arteries were isolated and vascular clips were used to control the renal segment arteries in the tumor area, and the renal segment arteries were isolated and blocked. The tumor and surrounding renal parenchyma were completely resected 0.5 to 1.0 cm from the tumor margin.

2.2.2 Results

Compared with total renal artery occlusion partial nephrectomy, the operation time and warm ischemia time were longer, and the intraoperative blood loss was more, and the differences were statistically significant (P < 0.05). One month after operation, the serum creatinine and urea nitrogen of the group undergoing superselective renal artery occlusion were lower than those of the group undergoing total renal artery occlusion, and the differences were statistically significant (P < 0.05) [11].

2.2.3 Complications

The injury of renal vein, renal pelvis, and ureter is a common complication when the renal artery is separated. As for postoperative complications, hematuria is usually caused by inadequate suture of renal pelvis and calyces during operation.

2.2.4 Advantages and limitations

It can not only provide a bloodless surgical field of view but also minimize the risk of ischemic injury and effectively protect renal function. Since only the branch of renal artery in the tumor area is blocked, the requirement of blocking time will be relaxed, which can allow more time for tumor resection and suture. However, compared with the main renal artery occlusion, the operation time is longer, the wound caused by vascular separation is larger, and the intraoperative bleeding is more [13].

2.3 Laser-assisted technique

2.3.1 Methods

The frontal laser fiber was used for vaporesection between 20 W and 25 W in all cases. The laser has the ability to coagulate and vaporize or cut, depending on the distance of the tip of the fiber from the tissue being resected (5 mm or 1–2 mm, respectively). After complete resection, the tumor was extracted through an endoscopic specimen bag via the 12- to 15-mm laparoscopic port [14].

2.3.2 Results

It is a good way to achieve minimally invasive surgery, helps to reduce bleeding in the case of complete tumor removal, and reduces the rate of positive margins [14].

2.3.3 Advantages and limitations

Carbon dioxide (CO2) laser was the first laser used in clinical practice for partial nephrectomy. However, when neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operated at 1064 nm (a 532-nm version exist for lithotripsy), it has a deeper length of tissue penetration (up to 1 cm) than CO2 laser. Nd:YAG laser revealed promising results with excellent cutting and coagulation properties, but the deeper tissue penetration increased the risk of damage to healthy kidney tissue [11]. The newer thulium:yttrium-aluminum-garnet (Th:YAG) laser was first introduced into clinical practice in 2005. It has a wavelength of 2013 nm in continuous wave mode and could offer complete absorption of laser energy in water, providing superior vaporization and hemostatic properties than those of other lasers, which means the laser allows both excellent coagulation and vaporization/cutting capabilities [15].

However, laser coagulation and vaporization create a problematic smoke plume that can obscure direct operative vision during resection, as well as the laser does not have the ability to seal larger arterial vessels greater than 2.0 mm. Therefore, the potential for bleeding increases with deeper endophytic tumors [16].

2.3.4 Complications

Severe carbonization sometimes will be produced because of difficulty in control [16].

2.3.5 Advance

An ideal laser setup should provide accurate and adequate tissue cutting and ablation without causing carbonization, splattering, or excessive smoke. In that case, the operator could avoid the necessity for irrigation and vision would be improved during resection. In addition, in such an ideal setup, hemostasis should be completed safely even in larger blood vessels without suture or additional hemostatic agents. Finally, the ideal laser for the operator should be fast and easy to use [16].

2.4 Radio frequency ablation (RFA)-assisted technique

2.4.1 Methods

After opening the renal fascia, the renal artery was identified and suspended. Fat was removed from the tumor and surrounding tissue. The tumor location was determined by direct vision and laparoscopic ultrasonography. Before RFA, all tumors were biopsied using a 22-gauge TruCore®. To avoid additional puncture, the electrode was introduced through the abdominal wall or a laparoscopic trocar. Intraoperative ultrasonography was used to guide electrode insertion and monitor ablation, which could ensure thermal energy cover the tumor base. RFA was performed for 1 to 3 cycles for 6 to 12 minutes each depending on tumor size and depth [17].

2.4.2 Indications

The median tumor size was 3.2 cm (2.8–3.9), and the majority (73.1%, n = 133) were exophytic in more than 50% of cases [17].

2.4.3 Results

Xiaozhi Zhao reported that the glomerular filtration rate did not differ before versus 12 months after radio frequency ablation-assisted surgery, and 3-year cancer specific, cumulative, and progression-free survival was 100%, 97.3% and 96.4%, respectively [17].

2.4.4 Advantages

As the mass with a rim of normal parenchyma is coagulated with RF energy, minimal blood loss and good visualization were achieved during tumor excision. It can also prevent or delay the decline of renal function to the maximum extent [18].

2.4.5 Limitations/complications

When comes to disadvantages, the first is an increased risk of positive surgical margins due to the difficulty in identifying the tumor margin. For another, the placement of electrodes and the thermal penetration could be complicated by calyceal injury, urinary leakage, and venous injuries. In contrast, the incidence of urinary leakage seems to be higher than that of traditional nephron-sparing surgery (NSS) or tumor enucleation (TE) [18, 19].

2.5 Microwave ablation (MWA)-assisted technique

2.5.1 Methods

After the tumor was localized and dissected, 1 to 3 cycles of MWA were performed lasting 2 to 8 min depending on the tumor size and depth. Zero-ischemia NSS can be achieved using the MWA-TE technique by placement of the MWA electrode to create a relatively avascular plane [5, 20].

2.5.2 Indications and contraindications

For the patients with a single, sporadic, unilateral, organ-confirmed and pathologically diagnosed renal cell carcinoma were included in the study of microwave ablation-assisted technology [14]. And the patients with multiple tumors on ipsilateral kidney, collecting system or renal vein invasion, previous renal surgery history of the operative kidney, or with other renal diseases (such as renal calculi, glomerular nephritis, etc.) are not suitable [5].

2.5.3 Results

In a 3-year follow-up of 100 patients who underwent laparoscopic partial nephrectomy (LPN), Moinzadeh et al. reported overall survival (OS) of 86%, cancer-specific survival of 100% and recurrence-free survival (RFS) of 100%. A recent study of microwave ablation-assisted tumor enucleation for renal cell carcinoma shows no significant difference between preoperative, postoperative, and latest eGFR [21]. And the OS of 3- and 5-year was 99.6% and 98.4%, respectively, and RFS was 98.2% and 95.8%, respectively. Microwave ablation-assisted zero-ischemia laparoscopic technology is considered to be a viable and effective nephron-sparing surgical technique for selected renal tumors, with a low perioperative complication rate and promising mid-to-long-term oncological and functional outcomes [5].

2.5.4 Advantages

MWA causes coagulated cell necrosis by inducing friction of water molecules. Compared to RFA, MWA is more effective for the ablation of larger tumors due to its heat generation mechanism. In clinical practice, we found that MWA has the advantages of higher intratumoral temperature and higher tissue ablation volume in a shorter ablation cycle than RFA [5, 20, 21, 22].

2.5.5 Limitations/complications

It carries the risk of affecting the diagnostic accuracy of the cut edge [5].

2.6 Hydro-jet-assisted technique

2.6.1 Methods

Hydro-jet-assisted minimally invasive partial nephrectomy (MIPN) is performed by blunt dissection and dissection of the renal parenchyma using extremely thin, high-pressure water flow. The spread of tumor cells may be caused when hydro-jet dissection is performed for malignant diseases.

2.6.2 Results

Gao and colleagues performed hydro-jet-assisted minimally invasive partial nephrectomy.The average operation time was (103.2 ± 24.5)min, the average intraoperative blood loss was (250.3 ± 80.6) ml, the average perirenal drainage tube induration was (6.3 ± 2.6) days, and the average postoperative hospital stay was (8.3 ± 1.6) days [23].

2.6.3 Complications

The spread of tumor cells may be caused when hydro-jet dissection is performed for malignant diseases [24].

2.6.4 Advantages and limitations

Water jet uses the kinetic energy of water to separate the human tissue, without any thermal damage, and will not cause damage to the important organs and surrounding tissues [25]. Water jet, with high tissue selectivity and protection, can achieve the purpose of accurate protection of blood vessels, nerves, and canals and reduce the possibility of accidental injury [23].

However, compared with other methods, the cutting speed of water jet is relatively low. Meanwhile, in the process of cutting with water knife, a large amount of water waste liquid will be produced, which may affect the observation of surgical field and the judgment of cutting surface [11].

3. Introduction of unassisted zero-ischemia surgery

3.1 Unassisted zero-ischemia partial nephrectomy

3.1.1 Methods

To obtain a bloodless field and, consequently, to perform precise tumor excision and renal reconstruction, contemporary partial nephrectomy (PN) techniques typically need hilar clamping, which necessarily imposes ischemic and reperfusion injuries upon the kidney [26]. The unassisted zero-ischemia PN technique aims to reduce or even eliminate these injuries and preserves renal function [27].

In 2011, Gill et al. introduced “Zero-Ischemia” partial nephrectomy as a new technique to perform minimally invasive partial nephrectomy (MIPN) with selective renal artery clamping. Firstly, to precisely guide the clamping of tumor-supplying branches, the feeding branch for the tumor is identified by angiographic evaluation or computed tomography angiography (CTA). Then followed is the microdissection of renal arterial branches. The hilar vessels should be preemptively prepared before the meticulous microdissection and clip ligation of the tertiary or quaternary renal arterial branch which dedicatedly supplies the tumor or the tumor-bearing segment of the kidney [26]. Related clinical studies have been carried out and suggested that selective renal artery clamping can achieve no inferior or even better effect than hilar clamping [28, 29].

Though the selective clamping technique reduces the ischemic renal injury, the ischemic area of selective renal artery clamping is still larger than the tumor area. In addition, it is necessary to dissect tertiary or quaternary renal arteries, prolong the operation time, and increase the stimulation of renal arteries. PN without clamping any artery called off-clamping technique aims to optimize this shortcoming. The operation is similar to on-clamping PN. The renal artery needs to be dissected and marked, but will not be clamped. Renal tumor and part of the kidney are dissected. Then the tumor is resected 0.5-1 cm away from the tumor edge without blocking the renal artery. The renal parenchyma is sutured continuously with inverted thorn thread, or bipolar electrocoagulation is given to stop bleeding and cover the hemostatic material. Drainage tube is indwelled after examination of no active bleeding [30].

3.1.2 Indications and contraindications

The indication for the application of zero-ischemia PN is not clear. Based on the indications and contraindications of on-clamping PN, the location, number, growth pattern (endogenous/exogenous), and intrarenal size of the tumor are the main factors to consider in operating this technique.

Zero-ischemia PN appears suited for medially located, whether in hilar, central, or polar sites. The medially located tumor or its bearing segment of the kidney is typically supplied by a dedicated secondary, tertiary, or quaternary branch [26]. However, tumors with dense or adherent perirenal fat or short segmental arteries may not be suggested to perform selective arterial clamping [31].

The application of off-clamping remains controversial. Whether under laparoscopic or robotic assist, unacceptable bleeding caused by off-clamping will lead to unclear visual field and difficult to complete high-precision surgery. Thus, off-clamping is limited to the tumors with favorably anatomical features (i.e. small, superficial, exophytic) and technically relatively easy [26].

3.1.3 Results and complications

The ideal goal of PN is to achieve Trifecta, that is, complete resection of the tumor ensures negative surgical margin, maximum preservation of normal nephron function, and avoidance of short-term and long-term complications. The negative surgical margin is the most important one [32].

In the study reported by GILL, SHAO, and NG, all patients who performed zero-ischemia PN achieve negative surgical margins [26, 28, 33]. In the study reported by SMITH and THOMPSON, the positive rate of tumor surgical margin is not significantly different between zero-ischemia PN and on-clamping PN [34, 35]. The study from WSZOLEK et al. tends to highly selective renal artery clamping can reduce the positive rate of the surgical margin, but the local recurrence rate and the 5-year survival rate in postoperative follow-up are similar [36].

Complications of zero-ischemia PN are similar to those of on-clamping PN due to the similar operation method. The study from WSZOLEK and THOMPSON revealed that on-clamping PN has a higher urine leakage rate and hemorrhage rate than zero-ischemia PN, but the results have no significant statistical significance [35, 36].

3.1.4 Advantages and limitations

That zero-ischemia PN is suited for anatomically favorable tumors results in on-clamping PN having a wider scope of application than zero-ischemia PN. During zero-ischemia PN, the increase in blood loss leads to unclear visual field and more difficult operation. The dissection of the tertiary or quaternary renal arterial branch prolongs the operation time.

But the ischemia time and area are reduced. It helps preserve more renal parenchyma and protects renal function. What’s more, for patients with cardiovascular complications, potential renal dysfunction, or old age, ischemia may lead to greater injury, so zero-ischemia technology has a comparative advantage [26].

3.2 Unassisted zero-ischemia tumor enucleation

3.2.1 Methods

For zero-ischemia tumor enucleation (TE), retroperitoneal fashion is typically accepted. The location of the tumor is determined according to the preoperative imaging data. The main renal artery needs to be isolated routinely. The resection initiated approximately 2 mm away from the tumor margin. After identifying the pseudocapsule, the surgeon took the pseudocapsule as an anatomic marker to enucleate the tumor from the surface to the bottom using blunt together with sharp dissection [37].

3.2.2 Indications and contraindications

Similar to PN, TE is mainly suitable for patients with lateral exophytic tumors with early stage, especially T1 renal cell carcinoma, and requires that the tumor has a pseudocapsule that has not been breached. Thus, for the endogenous tumor, the large intrarenal tumor, and the tumor have breached the pseudocapsule, zero-ischemia tumor enucleation is not a suitable operation. In addition, the zero-ischemia technique should not be applied to patients with severe bleeding tendency or severe anemia. For T2 renal cell carcinoma, whether using this technique should base on the anatomical features and techniques of surgeons.

3.2.3 Results and complications

The curative effect of simple enucleation (SE) of renal tumors provides a reference for zero-ischemia tumor enucleation. For localized renal cell carcinoma, there is no significant difference in the positive rate of surgical margin, local recurrence rate, and survival rate between SE and PN [2]. Minervini reported a case of 127 patients who performed robot-assisted SE with a median follow-up of 61 months. There was no recurrence in situ [38]. The 10-year tumor-specific survival rate of SE was 97% [39].

Complications of zero-ischemia enucleation include postoperative bleeding, urinary fistula, short-term and long-term decline of renal function caused by reduced renal parenchyma, and postoperative infection.

3.2.4 Advantages and limitations

Compared with PN, TE preserves more renal parenchyma to ensure better renal function but has a smaller scope of application due to the oncological and anatomical requirements [37].

Compared with off-clamping TE, the incidence of CKD of zero-ischemia TE is lower [40], and the reduction rate of postoperative GFR is lower [28]. The indexes such as creatinine in the zero-ischemia TE are also better than those in off-clamping TE [18]. But the intraoperative blood loss was higher.

3.3 Sequential preplaced suture Renorrhaphy technique

3.3.1 Methods

The method of this surgery was firstly described in 2013 by Emad et al. [41]. It is roughly the same as minimally partial nephrectomy in the process before tumor resection. Notably, sequential preplaced suture renorrhaphy technique is to excise the renal tumor between the tumor edge and the suture replaced through the tissue adjacent to the tumor and modifying placement of the suture real time until the mass is completely excised.

3.3.2 Indications and contraindications

Similar to other zero-ischemia minimally invasive partial nephrectomy surgeries, sequential preplaced suture renorrhaphy technique is mostly applicable to patients who require eliminating warm ischemia urgently, such as those with solitary kidneys or multiple tumors. As for the size and location of the tumor, it is practical for treating RCCs with small tumor sizes, especially whose diameter is smaller than 3 cm and which are exophytic and peripheral renal tumors. In other words, this technique is limited for treating hilar located tumors.

3.3.3 Results and complications

The results of this surgery were not worse than other MIPNs. There did not exsit a statistically significant difference between preoperative and 12-month postoperative creatinine and eGFR values [42]. As shown in a previous study [41], median estimated blood loss (EBL) was 192.5 mL while median operative time was 160 minutes, which were similar to other zero-ischemia surgeries. What is more, according to the postoperative pathology findings in multiple investigations, almost all of the tumors treated with it had negative surgical margins and were completely eliminated. After the surgery, postoperative ileus, blood transfusion, and deep vein thrombosis were the main postoperative problems. Another study found the average operating duration was 75 minutes and a 60-ml average blood loss [43]. All 14 cases had negative surgical margins, and there was no postoperative bleeding or urine leakage after surgery. There were no signs of recurrence on a follow-up CT conducted 1–6 months after surgery. However, results of this surgery still need long-term follow-up.

3.3.4 Advantages and limitations

Compared with other surgeries which need warm ischemia, it avoids renal ischemia reperfusion injury and preserves more renal function. Compared to other straightforward excision without hilar clamping, it improves visibility as a result of less bleeding and helps to excise less normal parenchyma and thereby minimize nephron loss. Moreover, suture placement can be more precisely adjusted in real time, which increases resection precision and lessens the likelihood of a positive margin.

The limited application of this method is to treat tumors with hilar locations. Besides, prepositioning the suture will compress and deform the tumor bed, making tumor removal challenging or erroneous. We still need more sample sizes and longer time to follow-up to verify its effectiveness and oncologic safety during the process of implementation [11].

4. Application of the three-dimensional visualization technology of renal vasculature

The arterial blood supply of renal cell carcinoma is diversified. Generally speaking, the main renal artery is the main blood supply artery for renal tumors. However, extrarenal blood supply arteries often participate in tumor angiogenesis, playing a very important role in tumor blood supply [44, 45]. Borojeni found that about 26 patients had multiple renal segmental arterial blood supply through renal arteriography of 60 patients with stage T1 renal carcinoma [46].

In recent years, with the development of minimally invasive technology and the implementation of the concept of “zero ischemia,” laparoscopic partial nephrectomy more often uses selective renal artery clamping. High-selective clamping of the segmental artery which irrigated the tumor can not only obtain good effect of blocking tumor blood supply but also effectively reduce the renal warm ischemia time of patients and reduce the risk of surgery. Francesco Porpigilia et al. studied 52 cases of robot-assisted partial nephrectomy and showed that compared with the control group, the preoperative hyperaccuracy three-dimensional (HA3D) reconstruction technology can accurately display the course and surrounding structures of renal tumor-related renal segment branches, thus improving the success rate of clamping renal tumor-related renal artery branches during operation [6].

As an imaging tool of digital medical technology, three-dimensional visualization uses computer image processing technology to process CT or MRI image data through the workstation, import the data into the three-dimensional visualization imaging software system for segmentation, fusion, calculation, rendering and other operations, and build a three-dimensional model. The model can describe and explain the precise location, spatial anatomy, shape and volume of target lesions, related organs and vascular systems from multiple angles and in an all-round way and can provide clinicians with intuitive visual experience and full quantitative information. It is of high value for accurate preoperative diagnosis, planning of individualized surgical programs, and prediction of surgical risks. Further studies have shown that three-dimensional visualization can clearly display the number, size, branching pattern, shape, and positional relationship with renal tumors of the aberrant renal arteries, thereby helping the surgeon to determine the anatomical shape of renal blood vessels and the location of ectopic blood vessels before surgery and provide accurate guidance intraoperative operation [47].

5. Advances in renal carcinoma complexity scoring systems

Currently available nephrometry scores can arbitrarily be grouped into those based on a visual anatomical assessment of a renal mass and those based on a mathematical assessment.

Most of the scores are included in this group because they are based on an immediate visual evaluation. The RENAL and PADUA scores assess the location of the tumor, its percentage of penetration into the kidney, and its relationship with the renal sinus or urinary collecting system [48]. The Diameter-Axial-Polar (DAP) score determines the size of kidney mass and distance from two reference lines: axial and polar lines [49]. The Zonal Nearness-Physical-Radius Organization (NePhRO) score provides five parameters that mirror RENAL and PADUA scores. The difference is that it divides the kidney into three zones (zone 1: kidney parenchyma; zone 2: medullary and sinus; and zone 3: collecting system and hilum) and employs another dimensional scale to determine renal mass dimension [50]. Otherwise, the Renal Pelvic Score (RPS) deviates from the previously mentioned scores. Indeed, it evaluates the presence of an intrarenal or extrarenal pelvis referring to a sagittal line which passes through the kidney hilum [51]. The Surgical Approach Renal Ranking (SARR), a different score, has the same characteristics as the RENAL, PADUA, and Zonal NePhRO scores but offers a scoring system range from 0 to 4, rendering it possible to achieve a more precise stratification of renal masses [52]. The majority of scores take the tumor’s longitudinal position into account; however, the Zhongshan score also takes into account the transversal tumor, which includes its lateral, central, and medial locations [53]. Recently, developments in the Simplified PAdua REnal (SPARE) nephrometry system has combined the key elements of both the nephrometry scores to create a maximum tumor size, exophytic rate, renal sinus involvement, and tumor rim location-based score [54]. The Arterial-Based Complexity (ABC) scoring system takes the order of vessels needed to be transected/dissected into account. The four scores (1, 2, 3S, and 3 H) evaluated are related to the neoplasm interaction with interlobular and arcuate arteries, interlobar arteries, segmental arteries, or in close proximity of the renal hilum, respectively [55]. The Peritumoral Artery Scoring System (PASS) is another score based on the vasculature [56]. Based on the number and diameter of the peritumoral arteries, this three-dimensional score assigns a complexity level to tumor dissection. The Mayo Adhesive Probability (MAP) score, in contrast to the scores stated above, assesses the perinephric fat thickness as a means to anticipate its adhesion to the kidney, which could result in a more complicated resection [57].

This category necessitates a thorough imaging examination and is based either on a mathematical or visual evaluation of the tumor. The first one, the Centrality Index (C-index), categorizes the complexity of the tumor according to the mathematical distance between the tumor and kidney center [58]. The Renal Tumor Invasion Index (RTII), which is the ratio of tumor invasion depth, is defined as the maximal distance that tumor invades into parenchyma and the parenchymal thickness of the kidney immediately adjacent to the tumor [59]. Both the tumor Contact Surface Area (CSA) and the Renal And Ischemia Volume (RAIV) use measurements of the mass radius and diameter. Additionally, the RAIV demands that the cross section of the resected and ischemized renal parenchyma be measured. [60, 61]. In a similar manner, the Zero Ischemia Index (ZII) shows the outcome of multiplying the tumor’s depth in the kidney parenchyma by its diameter. [62]. The Coefficient, Location, Anterior boundary, Multi-boundary, and Posterior boundary (CLAMP) score is the only used to determine the complexity of vascular. This three-dimensional (3D) imaging-based score assesses the anatomy of the arteries that supply the renal tumor. This instrument could estimate the effectiveness of segmental artery clamping [62].

The Mayo Clinic thrombus classification is widely used to describe levels of inferior vena cava tumor thrombus and is significant to guide the operation for renal cell carcinoma with venous thrombus in the open era [7]. But in the minimally invasive surgery era, Prof. Zhang et al. summarized a large number of surgical experiences of renal cell carcinoma with venous thrombus and put forward the “301 classification” system. The system based on anatomical landmarks in which one grade corresponds to one surgical strategy improves surgical choice in the treatment of renal cell carcinoma with venous thrombus. The right renal vein tumor thrombus was Level 0, and the surgical strategy was radical resection of the right kidney; left renal vein tumor thrombus can be divided into Level 0a and 0b according to whether it exceeds the superior mesenteric artery [8]. In 0a, radical resection of the left kidney is performed. In 0b, left renal artery embolism is performed before operation. First, the left renal vein and inferior vena cava are disconnected in the left lateral position, and then radical resection of the left kidney is performed in a different position. The inferior vena cava tumor thrombus below the first porta hepatis was level I, which did not need to turn over the liver, only needed to lift the liver and cut off 1–3 short hepatic veins. The level from the first porta hepatis to the second porta hepatis is level II, and it is necessary to turn the right hepatic lobe, without blocking the hepatic blood flow, and disconnect 2 to 5 short hepatic veins. The level from the second hepatic portal to the diaphragm is Level III, which requires turning the left and right hepatic lobes, and blocking the portal blood flow. During the operation, venous-venous bypass is performed according to the situation, and more short hepatic veins are cut off; Level IV is above the diaphragm [63]. Cardiopulmonary extracorporeal circulation should be established to block the superior vena cava and the inferior vena cava above the diaphragm. Thoracoscopic surgery should be performed to remove the atrial tumor thrombus and then block the hepatic portal vessels, and the distal inferior vena cava and its branches. For level 0 or 0a tumor thrombus, laparoscopic surgery is the first choice. For 0b or inferior vena cava tumor thrombus, robotic surgery is the first choice. If the tumor is large, has a complex surgical history, and the function of organs such as the heart is not complete, and it is necessary to shorten the operation time or establish venous bypass, open surgery is the first choice.

6. Conclusion

Most cases of RCC have no clinical symptoms but are diagnosed accidentally. With the development of diagnostic technology, the incidence of patients diagnosed with RCC has increased rapidly over the past decades. For the majority of patients diagnosed with RCC, choosing the appropriate treatment is the primary means to improve their prognosis. Therefore, knowing the latest surgical progress and being familiar with the renal carcinoma complexity scoring system could help doctors design more individualized and appropriate surgical procedures for patients, allowing surgeons to preserve more renal parenchyma while fully removing the tumor.