Comparative analysis of marginal profit between da Vinci SP and multi-port systems in colorectal cancer surgery: a single-center descriptive cost-accounting study.

Because fixed costs such as capital investment, lease-related expenses, and depreciation vary substantially according to institutional case volume, timing of platform introduction, and local accounting policy, direct cross-platform comparison based on total cost may be difficult to interpret in routine practice. This study aimed to descriptively compare marginal profit rates of conventional laparoscopy (Lap), the da Vinci single-port (SP) system, and the da Vinci multi-port platforms in colorectal cancer surgery using institutionally standardized running costs. We retrospectively reviewed patients with resectable primary colorectal cancer who underwent minimally invasive surgery at our institution between October 2024 and December 2025. The primary economic outcome was marginal profit rate (MPR), defined as the proportion of reimbursement revenue remaining after subtraction of institutionally standardized running costs. These running costs included materials, personnel, and time-based operating room allocations. Fixed costs, including capital investment, lease-related cost, and depreciation, were excluded to focus on procedural cost efficiency during routine clinical operation. Because this study was designed as a descriptive cost-accounting analysis, no formal hypothesis testing was performed; however, 95% confidence intervals (CIs) were calculated for descriptive transparency. In an additional subgroup analysis, multi-port robotic cases were separated into da Vinci Xi and da Vinci 5. Of the 607 colorectal resections initially assessed during the study period, 575 cases were included in the final analysis. In the original platform-level comparison, laparoscopic surgery showed the highest marginal profit rates across evaluated procedures. Among robotic approaches, the SP group showed numerically higher marginal profit rates than the pooled multi-port group in colectomy and rectal resection. In the additional subgroup analysis, the cohort consisted of 118 laparoscopic cases, 131 SP cases, 258 Xi cases, and 68 da Vinci 5 cases. In colectomy, mean MPRs were 53.3% (95% CI, 52.4–54.3) for laparoscopy, 33.4% (95% CI, 32.1–34.7) for SP, 28.1% (95% CI, 27.2–29.0) for Xi, and 19.1% (95% CI, 16.3–21.9) for da Vinci 5. In rectal resection, the corresponding values were 61.5% (95% CI, 59.7–63.2), 43.3% (95% CI, 41.2–45.4), 40.8% (95% CI, 39.8–41.7), and 35.6% (95% CI, 33.0–38.3), respectively. In this single-center descriptive cost-accounting study using institutionally standardized running costs excluding depreciation, the da Vinci SP platform showed numerically higher marginal profit rates than the pooled multi-port cohort. Additional separation of the multi-port group suggested heterogeneity between Xi and da Vinci 5 in this early institutional experience. These findings do not establish economic superiority of any specific platform, but rather suggest that workflow behavior and resource utilization patterns may influence procedural profitability under real-world robotic colorectal surgery conditions. Further studies incorporating case-mix adjustment and device-level consumable analysis are warranted.