Real-World Data of Retroperitoneal Tumor Surgeries Performed by Gastroenterological Surgeons in Japan: Analysis Based on the National Clinical Database.

Background: Retroperitoneal tumors (RPTs) are rare and anatomically complex neoplasms, for which surgery remains the mainstay of treatment. However, real-world data on their surgical management in Japan have been limited. Objective: To describe the clinical characteristics and short-term outcomes of patients undergoing resection for RPTs in Japan, based on data from gastroenterological surgical practice. Methods: This study analyzed data from the Japanese National Clinical Database (NCD) for gastroenterological surgery. A total of 4948 patients with RPT who underwent surgery between 2019 and 2021 were included. Results: There were 2360 men (47.7%) and 2588 women (52.3%), with a median age of 66 years. RPTs were histologically classified as malignant in 75.3% and benign in 24.7% of cases. The median operative time was 205 min, and the median blood loss was 150 mL. Postoperative complications occurred in 23.9% of patients, with 7.5% experiencing severe complications (Clavien-Dindo grade III or higher). The 30 day postoperative mortality rate was 0.5%, and the perioperative mortality rate was 1.0%. Conclusion: This analysis demonstrates that a substantial number (approximately 1650 per year) of RPTs surgeries are performed annually by gastrointestinal surgeons in Japan, and that the short-term surgical outcomes are acceptable. These data provide an important reference to exhibit the current surgical practice in Japan and to develop future strategies for RPTs.