(UroToday.com) In anticipation of the 2021 American Urological Association (AUA) Annual Meeting which is being held, in a delayed fashion, in September, the AUA hosted a “May Kick-Off Weekend” which highlighted a variety of important topics in both benign urology and urologic oncology. Saturday morning, W. Marston Linehan led a course entitled “Diagnosis and Management of Localized, Locally Advanced and Advanced Kidney Cancer” along with Ramaprasad Srinivasan, David McDermott, and Mark Ball.
Following Dr. Linehan’s talk on the genetic basis of kidney cancer, Dr. Ball presented on decision making during complex partial nephrectomy, highlighting AUA guidelines on this topic. He focused on two key questions, first, when to perform partial nephrectomy and then, second, decision making during partial nephrectomy including a variety of technical questions.
Considering candidates for partial nephrectomy, Dr. Ball described a so-called “Goldilocks” approach: this recognizes that some patients due to a combination of patient and tumor factors may be better served with active surveillance (“too cold” for partial nephrectomy) and others may be more appropriately treated with radical nephrectomy (“too hot” for partial nephrectomy) while others are appropriate for partial nephrectomy. In keeping with AUA guidelines, he emphasized that surveillance is warranted for patients with small renal masses, particularly those less than 2 cm, and that this approach should be prioritized when the anticipated risks of intervention or competing risks of death outweigh the oncologic benefits of treatment. In contrast, radical nephrectomy should be preferred where there is an increased oncologic potential, particularly where there is high tumor complexity, there is no history of pre-existing chronic kidney disease, and the contralateral kidney is normal.
Thus, partial nephrectomy should be considered in the intermediate situation in which the anticipated oncologic benefits of intervention outweigh risks of treatment and competing risks of death but the disease is not sufficiently advanced as to require radical nephrectomy or renal function is such that nephron preservation is prioritized.
In the context of partial nephrectomy, Dr. Ball highlighted four axes of decision making, including open vs robotic surgery, transperitoneal vs retroperitoneal approaches, enucleation vs wide excision, and clamped vs off-clamp resection.
Considering the first of these, Dr. Ball emphasized that surgeon experience and comfort and should be foremost in the decision making regarding open versus robotic approaches. However, open surgery may be preferred if cold ischemia is warranted, for certain patients on the basis of their tumor histology or underlying genetic syndromes, and potentially for those with prior renal surgery. However, he highlighted guidance from the AUA guidelines which suggested that a minimally invasive approach “should be considered when it would not compromise oncologic, functional, and perioperative outcomes”. When open approaches are used, he highlighted that a flank mini-incision can be utilized.
Further, while prior renal surgery was previously considered a reason to pursue open surgery, he emphasized that there is an increasing role for robotic surgery in this setting. They have recently published that a robotic approach in re-operative cases was not only safe, but that complication rates and blood loss were lower than those undergoing open surgery. In the context of re-do robotic surgery, he suggested consideration of off-clamp excision for exophytic tumors to avoid having to dissect the hilum or, when clamping is required, to consider en bloc clamping to avoid trying to dissect the artery and vein free of each other. He further suggested that the use of a ureteral catheter can facilitate identification of the ureter, that preservation of Gerota’s fashion can preserve tissue planes, and that ultrasound should be used early and often including for identification of the ureter and hilum in addition to the tumor.
A systematic review of open and robotic partial nephrectomy included 34 non-randomized studies and more than 60,000 patients. This demonstrated that robotic approaches were associated with lower blood loss and transfusion, less postoperative complications and readmissions, shorter length of stay, less postoperative renal dysfunction but longer operative time.
Among robotic approaches, Dr. Ball then considered transperitoneal versus retroperitoneal approaches. He emphasized that transperitoneal remains the most commonly utilized approach, due to the familiarity of the anatomy and working space afforded. However, the retroperitoneal approach is particularly beneficial for posterior tumors allowing quicker access and better visualization of the base of these tumors. However, this comes at the expense of less familiar anatomy and less working space. While this is preferable for tumors on the posterior aspect of the kidney, it is better for mid and upper pole tumors as lower pole tumors may be too close to the camera and instruments for facile operating.
Dr. Ball highlighted that the comparative literature on these approaches is not very robust, totaling 7 retrospective studies of ~1400 patients.
He then moved to consider the resection approach, enucleation versus wide excision. As highlighted previously in Dr. Linehan’s talk, some syndromes routinely call for enucleation while others favor wide resection. In patients with sporadic tumors, both approaches can be considered. Tumor enucleation has the benefit of preserving more parenchyma and allowing direct visualization of the tumor which can allow for the identification of important structures including the collecting system. Further, this may be accomplished off-clamp.
Notably, AUA guidelines emphasize that negative surgical margins should be the priority for any partial nephrectomy. Thus, while data from Cleveland Clinic suggest that tumor enucleation may facilitate off-clamp surgery, positive margin rates may be higher.
Finally, Dr. Ball considered the question of whether to perform partial nephrectomy clamped or off-clamp. He suggested that off-clamp surgery should be indicated in patients with multiple tumors which are not amenable to extended warm ischemia, those with a solitary kidney, those with existing chronic kidney disease, those with prior renal surgery and a scarred hilum, and those in which future kidney surgeries are anticipated in order to prevent scarring of the hilum. Off-clamp surgery goes, in his view, hand-in-hand with tumor enucleation both in terms of preservation of renal function and in terms of bleeding risk. As a result of the increased likelihood of bleeding associated with off-clamp partial nephrectomy, Dr. Ball suggested using a lap pad or bolster to allow for manual compression of the renal defect. While there are significant limitations to the data, a systematic review suggests that off-clamp partial nephrectomy is associated with similar transfusion requirements, complications, and positive surgical margins.
Integrating all of these intra-operative considerations, Dr. Ball highlighted that he most typically performs robotic transperitoneal off-clamp enucleation given his population of patients with hereditary or sporadic multi-focal tumors. This approach yields the maximal preservation of renal function while minimizing complications.
To highlight these decision-making considerations, he then presented a number of case examples, walking the audience through his decision-making regarding the treatment approach. In one of these, he highlighted a case of an endophytic tumor. While this is often considered for radical nephrectomy, he described a robotic enucleation approach (on-clamp due to the bleeding risk associated with an endophytic tumor). In these tumors, rather than excising overlying or adjacent tissue, he highlighted the goal of preserving the parenchyma overlying tumor.
A different case highlighted the value of intra-operative ultrasound which identified the main renal vessels in direct contact with the tumor. Thus, deeming this “too hot” for partial nephrectomy, they converted to radical.
Concluding, Dr. Ball emphasized that the decision to perform partial nephrectomy is based on a weighting of the oncologic risk of the tumor and the competing risks of surgery. During a partial nephrectomy, decisions regarding treatment approaches depend on patient, tumor, and surgeon factors.
Presented by: Mark Ball, MD, attending surgeon in the Urologic Oncology Branch of the National Cancer Institute, Associate Program Director of the Urologic Oncology Fellowship Program, Center for Cancer Research
Written by: Christopher J.D. Wallis, Urologic Oncology Fellow, Vanderbilt University Medical Center, @WallisCJD on Twitter during the AUA2021 May Kick-off Weekend May 21-23