Robot-Assisted Retroperitoneal Tumor Resection: Evaluation of Its Safety, Feasibility, and Implementation in a Japanese Clinical Setting.

Background Robot-assisted resection of retroperitoneal tumors has been increasingly reported worldwide; however, its clinical implementation in Japan remains limited and is not yet approved under the national health insurance system. We aimed to evaluate the safety and feasibility of this approach in a Japanese clinical setting. Methods We retrospectively reviewed seven consecutive patients who underwent robot-assisted retroperitoneal tumor resection at a high-volume cancer center between July 2024 and September 2025. Patient selection was based on tumor size, location, and absence of extensive vascular invasion. All procedures were performed by an experienced robotic surgeon. Perioperative outcomes, including operative time, blood loss, conversion rate, complications, and pathological results, were analyzed. Results Median tumor diameter was 35 mm (range, 15-81 mm), including three tumors ≥60 mm. All procedures were completed robotically without conversion. No intraoperative complications or transfusions occurred. All patients achieved R0 resection without tumor rupture. Median hospital stay was six days, with no major complications or readmissions. At the 17-month median follow-up, all patients were alive without recurrence. Conclusions These findings suggest that robot-assisted resection is a safe and feasible minimally invasive approach in selected patients and support further prospective evaluation and broader implementation in Japan.