Planning Operative Strategy Using a Digital Renal Artery Clamping Tool

BACKGROUND:

For patients diagnosed with localized kidney cancer, two main options exist to surgically remove the kidney tumor. During radical nephrectomy (RN), the entire kidney is removed. During partial nephrectomy (PN), only the tumor is resected, safeguarding the function of the remaining healthy kidney tissue. This last procedure is preferred, but not always technically feasible. To resect only the tumor, a balance has to be found in the clamping approach: clamping the blood supply to the kidney assures bloodless tumor resection, yet compromises the postoperative renal function due to the temporary ischemia. Tumor resection without clamping on the other hand, might lead to substantial blood loss. That is why "selective clamping" (SC) is proposed. In this approach, only those selective arteries are clamped that perfuse the zone including the tumor. The main drawback of this strategy is that it is often not clear which arteries should be clamped based on standard preoperative imaging, while misjudgment can lead to a high-risk surgery with excessive bleeding or prolonged ischemia time. Therefore, RN is currently recommended when PN is considered not feasible. Better prediction of individual kidney perfusion will allow to perform more frequently a PN and thus save healthier kidney tissue. Additionally, it is difficult for patients to assess their own individual oncological situation based on 2D CT images.

With this project, the investigators want to offer the surgeon an easy-to-use virtual planning tool that facilitates the decision-making process regarding the feasibility of PN and the corresponding optimal clamping strategy. This tool uses virtual 3D models based on CT scans, to visualize precise information on the different anatomical structures and perfusion zones. This may also improve patients' understanding of their own individual situation. The proposed new tool (DIPLANN-tool) for predicting kidney perfusion zones on a segmented 3D model during robot-assisted partial nephrectomy (RAPN) for localized renal cancer demonstrated high accuracy when planning selective clamping (SC) for RAPN. However, the tool's clinical added value still needs to be confirmed. Therefore, a randomized controlled trial using a study and control group is the preferred study design.

DESIGN:

A confirmatory, multicentric, unblinded, randomized, controlled, pivotal trial using parallel group assignment and stratified randomization.

Experimental group: the use of the DIPLANN model + conventional CT imaging for preoperative planning and perioperative guidance.

Control group: the use of only conventional CT imaging for preoperative planning and perioperative guidance (= current standard of care).

METHODOLOGY:

Sample size calculation: 235 patients.

Patients will be randomized according to a 1:1 allocation ratio to either the experimental group (the DIPLANN-tool in combination with conventional CT imaging) or the control group (conventional CT imaging alone), using permuted block randomization with blocks of varying size.

Randomization will be stratified on the following variables:

• Whether SC is deemed possible according to the DIPLANN-tool in combination with conventional CT imaging or on conventional CT imaging alone, as assessed by an independent surgeon (between inclusion and randomization) who will not be not involved in the RAPN surgical procedure (yes vs no).
• Hospital where surgery is performed.
• PADUA classification (low (<8) and intermediate (8-9) vs high-risk (>9)). In case of multiple masses, the mass with the highest individual PADUA classification will be used.

PRIMARY OBJECTIVE:

To assess if the DIPLANN-tool in combination with conventional CT imaging is superior to conventional CT imaging alone, with respect to planning and performing as planned a SC strategy during RAPN, in patients diagnosed with localized kidney cancer who are planned to undergo renal cancer surgery and in whom SC is deemed possible either according to the DIPLANN-tool in combination with conventional CT imaging or according to conventional CT imaging only, as assessed between inclusion and randomization by an independent surgeon.

SECONDARY OBJECTIVES:

• To assess if the DIPLANN-tool in combination with conventional CT imaging is superior to conventional CT imaging alone, with respect to planning and performing as planned a SC strategy during RAPN, in patients diagnosed with localized kidney cancer who are planned to undergo renal cancer surgery.
• To compare the DIPLANN-tool in combination with conventional CT imaging to conventional CT imaging alone with respect to: patients' health, patients' insight, and surgeons' benefits.

ENDPOINTS:

The primary endpoint is planning and performing as planned a SC strategy. Secondary endpoints include patients' health, patients' insight and surgeons' benefits.

Extended listing of all outcome measures: see below.

Inclusion criteria

• aged 18 years or above
• cT1-2 N0 M0 renal mass
• planned to undergo RAPN
• multiphase CT scan with arterial phase available
• voluntary given and written informed consent
• sufficient in at least one of the study languages: Dutch, English, French

For the primary objective, SC needs to be deemed possible either according to the DIPLANN-tool in combination with conventional CT imaging or according to conventional CT imaging only, as assessed by an independent surgeon (between inclusion and randomization) who will not be involved in the RAPN surgical procedure, in order to be included in the analysis set. On the DIPLANN tool, SC is deemed feasible if >= 90% tumor ischemia and <= 70% renal parenchyma ischemia can be achieved. If these criteria are met, but it is technically or anatomically not feasible according to the independent surgeon to perform SC, he can deviate from these criteria and thus claim SC is not deemed possible. The results for the total population (patients in which SC is deemed possible AND impossible pre-operatively by an independent surgeon) will also be analyzed as a secondary objective.

Exclusion criteria

• > 3 ipsilateral renal masses
• women who are pregnant or breastfeeding
• previous renal surgery that is expected to complicate renal cancer surgery
• cT ≥ 3
• planned off-clamp resection
• cognitive disorder which impedes with completing study questionnaires