Editor’s Note: The 2026 Pujiang Urological Oncology Academic Conference was held in Shanghai, bringing together experts from China and abroad to discuss standardized diagnosis and treatment, innovations in surgical techniques, and advances in precision medicine in urological oncology. Completely endophytic renal tumors are particularly challenging because they lack visible landmarks on the renal surface, making intraoperative localization, margin control, and preservation of the collecting system and renal vasculature difficult. Oncology Frontier – UroStream invited Professor Nan Liu of Chongqing University Cancer Hospital for an interview to discuss preoperative assessment, intraoperative localization and tumor resection strategies, and nephron-sparing decision-making for highly complex renal tumors, sharing his clinical experience and perspectives on surgical techniques.Preoperative Assessment: Transforming “Invisible” Tumors into Plannable Surgical Targets
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Completely endophytic renal tumors lack clear surface landmarks, posing greater challenges for intraoperative localization, margin control, and preservation of the collecting system and renal vasculature. For patients scheduled to undergo robot-assisted partial nephrectomy, what are the key factors that should be assessed preoperatively?
Professor Nan Liu: Completely endophytic renal tumors typically receive 3 points for the “E” component of the R.E.N.A.L. Nephrometry Score, indicating that the tumor is completely surrounded by renal parenchyma and cannot be directly visualized from the renal surface during surgery. Therefore, preoperative three-dimensional imaging reconstruction is particularly important. Based on contrast-enhanced CT and other imaging modalities, we need to systematically assess the tumor’s size, location, and morphology, as well as its spatial relationship with the major renal arterial and venous branches, renal sinus, and collecting system.
First, the surgical approach should be determined. Tumors located predominantly on the anterior aspect of the kidney are generally more suitable for a transperitoneal approach, whereas predominantly posterior tumors may be approached retroperitoneally, commonly referred to as the flank approach. The final choice should be based on the tumor depth, renal hilar vascular anatomy, and the surgeon’s experience.
Second, the resection pathway should be anticipated. For tumors with a regular, approximately spherical shape, complete resection along the tumor capsule or pseudocapsule may be possible once the tumor boundaries have been accurately identified. For irregularly shaped or deeply located tumors, limited renal parenchymal fenestration or wedge-shaped incision may be required to adequately expose the tumor margins.
Third, a multimodal localization system should be established. Intraoperative ultrasound remains an important tool for determining tumor location, boundaries, and depth. However, its effectiveness can be influenced by the tumor’s echogenicity and the operator’s experience. Surgeons need to integrate intraoperative ultrasound with the preoperative three-dimensional model and the real-time surgical field to dynamically assess the tumor’s relationship with the vasculature and collecting system.
Three-dimensional models can be used not only for surgical planning but also for preoperative team discussions and communication with patients. Through virtual surgical simulation, potential difficulties, bleeding risks, the need for collecting-system repair, and the possibility of conversion to radical nephrectomy can be identified in advance, allowing risk communication and intraoperative preparation to be brought forward.
Intraoperative Navigation: Multimodal Localization and Individualized Tumor Resection
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During surgery, how can imaging reconstruction, intraoperative ultrasound, renal parenchymal incision planning, and blood-flow control strategies be integrated to improve the accuracy and safety of resection for completely endophytic tumors?
Professor Nan Liu: The key step in surgery for completely endophytic renal tumors is precise localization. Once the tumor boundaries and depth have been clearly established, subsequent resection can be performed on a more reliable basis. For these complex tumors, we currently primarily use robotic surgery. Some studies have suggested that, compared with conventional laparoscopy, robotic surgery may offer advantages in operative precision, warm ischemia time, and complex reconstruction, providing technical support for minimally invasive nephron-sparing surgery in completely endophytic tumors.
Several intraoperative localization techniques can currently be used:
First, intraoperative ultrasound. This is the most commonly used method. However, as mentioned above, its visualization is affected by tumor echogenicity and operator experience.
Second, coil localization. After the tumor location is precisely identified by CT before surgery, a coil can be placed through an interventional procedure approximately 1–3 cm deep from the tumor margin, with the tail left outside the renal capsule. This can then be used as an intraoperative landmark to identify the tumor location.
Third, near-infrared fluorescence imaging. Following intravenous administration of indocyanine green (ICG), near-infrared imaging integrated into the robotic system can display areas with abundant blood supply. However, distinguishing hypovascular tumors from normal renal parenchyma may be difficult. One potential approach is superselective microarterial embolization: ICG can be mixed with an iodized-oil embolic agent at a ratio of 2:1 and selectively injected into the tumor-feeding artery. This allows the tumor to be visualized under near-infrared light, while microembolization reduces ICG washout and thereby enhances intraoperative visualization.
Regarding renal parenchymal incision, relatively superficial tumors can be approached along the anticipated tumor boundary. Once the tumor margin is identified, resection can be completed. For deeply located tumors covered by a thick cortical layer, a small amount of normal renal parenchyma may be removed to create a “window,” or a wedge-shaped incision may be performed when necessary. This facilitates adequate visualization of the tumor margin, enables precise resection of irregular lesions, and reduces the risk of a positive surgical margin.
Blood-flow control should be individualized according to the tumor-feeding branches identified on preoperative three-dimensional reconstruction. The objective is to control bleeding while minimizing warm ischemia time and preserving as much normal renal parenchyma and renal function as possible.
Nephron-Sparing Decision-Making: Balancing Technical Feasibility with Meaningful Patient Benefit
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Completely endophytic renal tumors lack clear renal surface landmarks and therefore present significant challenges for intraoperative localization, margin control, and preservation of the collecting system and renal vasculature. For patients considered for robot-assisted partial nephrectomy, what factors are most important in preoperative assessment?
Professor Nan Liu: The decision to pursue nephron-sparing surgery should not be based solely on whether the procedure is technically feasible. More importantly, we need to determine whether meaningful renal function can be preserved while maintaining oncological safety. Current domestic and international guidelines generally support considering partial nephrectomy as the preferred approach for T1 renal tumors. For T1a tumors, defined as lesions no larger than 4 cm, nephron-sparing surgery should be pursued whenever feasible. For T1b tumors, partial nephrectomy can also be actively considered when technically feasible and oncological risks are controllable. For tumors with higher stage or highly complex anatomy, individualized assessment should take into account the patient’s renal function needs and the experience of the treating center; the indications should not be routinely expanded.
Expansion of the indications for partial nephrectomy should meet the following requirements:
First, patient benefit must be based on oncological safety. Preoperative assessment should comprehensively consider tumor size and location, its relationship with the renal hilar vessels and collecting system, contralateral kidney function, baseline renal function, comorbidities, and life expectancy. If imaging suggests significant involvement of the collecting system, the patient presents with gross hematuria, or achieving a safe surgical margin is expected to be difficult, the necessity and feasibility of nephron-sparing surgery should be carefully reconsidered.
Second, technical capability must match institutional experience. Completely endophytic tumors, hilar tumors, and lesions with complex relationships to major vessels or the collecting system place substantial demands on both the surgeon and the multidisciplinary team. Highly complex nephron-sparing procedures should preferably be performed at high-volume centers with extensive robotic experience and comprehensive imaging and interventional support. The absence of a robotic platform does not necessarily make surgery impossible, but attempting complex nephron-sparing surgery without sufficient experience may increase the risks of tumor rupture, positive surgical margins, major complications, or intraoperative conversion to radical nephrectomy.
The goal of ideal nephron-sparing surgery is not simply to “leave the kidney in place.” Rather, it is to achieve complete tumor removal while preserving as many functioning nephrons as possible and keeping the risks of bleeding, urinary leakage, recurrence, and metastasis within an acceptable range. Only through comprehensive assessment of the patient, tumor characteristics, and institutional capabilities can clinicians make a sound decision that appropriately balances technical feasibility with genuine patient benefit.
Summary
Professor Nan Liu’s presentation provided a systematic overview of precision strategies for robot-assisted partial nephrectomy of completely endophytic renal tumors—from contrast-enhanced CT and three-dimensional reconstruction for selecting the surgical approach and planning the procedure, to the integrated use of intraoperative ultrasound, coil localization, and ICG-based near-infrared fluorescence imaging, and finally to careful nephron-sparing decision-making for highly complex renal tumors.
The expansion of indications for nephron-sparing surgery should always be based on oncological control and guided by long-term patient benefit, while remaining aligned with the experience and technical capabilities of the treating center.
Professor Nan Liu
Chongqing University Cancer Hospital
