Patient Reported Outcomes and Different Renal Artery Clamping Techniques During Robot Assisted Kidney Resection (RAPTOR)

Renal cell carcinoma can be managed with surgical excision, surveillance, or ablative techniques. For localized renal tumors, robot-assisted partial nephrectomy (RAPN) has become a standard treatment because it preserves renal function while maintaining oncological outcomes comparable to radical nephrectomy. Two minimally invasive surgical approaches are commonly used for RAPN: the transperitoneal approach and the retroperitoneal approach. Although both techniques are considered safe and effective, existing literature has mainly focused on perioperative outcomes such as operative time, blood loss, warm ischemia time, complications, and oncological results. Limited data are available regarding patient-reported outcomes, including postoperative pain, recovery, and quality of life.

The RAPTOR study is a prospective clinical study designed to evaluate both patient-reported outcomes after kidney surgery and surgical outcomes associated with different renal artery declamping strategies during robot-assisted partial nephrectomy.

The first study component (PROMs arm) will compare patients undergoing robot-assisted partial nephrectomy through either a transperitoneal or retroperitoneal approach. The primary objective is to determine whether the retroperitoneal approach results in reduced postoperative pain compared with the transperitoneal approach. Secondary objectives include comparisons of postoperative opioid consumption, recovery after surgery, quality of life, duration of sick leave, perioperative outcomes, oncological outcomes, and long-term renal function.

The second study component (clamping arm) is a randomized comparison of two commonly used renal artery declamping strategies during robot-assisted partial nephrectomy. During standard declamping, the renal artery clamp remains in place until all renorrhaphy suturing has been completed. During early declamping, the renal artery clamp is removed after closure of the resection bed but before completion of renorrhaphy. Early declamping may reduce warm ischemia time and thereby preserve renal function, but concerns remain regarding the possibility of increased bleeding. Existing evidence suggests that early declamping may reduce ischemia time without clinically relevant increases in blood loss or complications; however, high-level prospective evidence remains limited.

Patients scheduled for surgery for renal cancer at Haukeland University Hospital will be screened for eligibility. Patients undergoing robot-assisted partial nephrectomy will be assigned to either a transperitoneal cohort or a retroperitoneal cohort according to tumor characteristics and surgeon preference. Patients undergoing other forms of kidney cancer surgery, including nephrectomy, will be enrolled as an observational control cohort for analyses involving patient-reported outcomes.

Within both partial nephrectomy cohorts, patients will undergo stratified block randomization in a 1:1 ratio to either early declamping or standard declamping. Randomization will occur after the surgical approach has been selected to ensure balanced allocation of declamping strategies within both surgical access groups.

Patient-reported outcomes will be assessed using validated Norwegian-language instruments. Pain will be measured using the Brief Pain Inventory (BPI), postoperative recovery using the Quality of Recovery-15 Norwegian version (QoR-15NO), and quality of life using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30). Assessments will be completed preoperatively (baseline), on the first postoperative day, at 6 weeks after surgery, and at 1 year after surgery.

The primary endpoint in the PROMs arm is change in postoperative pain from baseline to postoperative day one, measured using the mean pain severity score from the Brief Pain Inventory. Secondary endpoints include opioid consumption during the first 24 postoperative hours, pain at 6 weeks and 1 year, postoperative recovery scores, quality-of-life scores, duration of sick leave, operative time, length of hospital stay, postoperative complications, positive surgical margins, transfusions, recurrence-free survival, disease-specific survival, overall survival, and long-term renal function measured by estimated glomerular filtration rate (eGFR).

The primary endpoint in the clamping arm is intraoperative blood loss during partial nephrectomy. Secondary endpoints include warm ischemia time, postoperative complications, transfusions, operative time, positive surgical margins, renal function, recurrence outcomes, and survival outcomes.

Perioperative variables collected will include operative duration, warm ischemia time, estimated blood loss, postoperative opioid use converted to morphine equivalents, pathology findings, complications graded according to the Clavien-Dindo classification, transfusions, length of stay, renal function, and oncological outcomes. Follow-up assessments will occur at 6 weeks, 1 year, 3 years, and 5 years after surgery. Long-term follow-up will include recurrence-free survival, disease-specific survival, overall survival, and renal function.

The study is expected to enroll approximately 120-150 patients. Sample size calculations indicate that 88 patients undergoing robot-assisted partial nephrectomy are required to detect a clinically meaningful difference in postoperative pain between surgical approaches and to evaluate non-inferiority of early declamping with respect to blood loss. Enrollment is expected to take approximately 2-3 years.

The study is conducted in accordance with the Declaration of Helsinki and applicable Norwegian regulations. Written informed consent will be obtained from all participants before enrollment. The patient-reported outcomes component is observational and presents minimal risk beyond completion of questionnaires. In the randomized declamping component, both interventions represent accepted surgical techniques currently used in clinical practice. An interim analysis is planned after approximately half of the randomized participants have been enrolled to assess safety and study conduct.