Postoperative C-Reactive Protein as a Marker of the Early Inflammatory Response in Robotic Versus Laparoscopic Minimally Invasive Surgery for Endometrial Cancer: A Propensity Score-Matched Analysis

Background/Objectives: Robot-assisted laparoscopic surgery (RALS) for endometrial cancer achieves outcomes comparable to those of conventional laparoscopy (Lap) but often requires a longer operative time, which may increase the early postoperative inflammatory response. We compared the postoperative day 1 (POD1) C-reactive protein (CRP) elevation between RALS and Lap and examined whether it was associated with the surgical platform or with patient- and procedure-related factors. Methods: This retrospective single-center study included 301 patients who underwent minimally invasive hysterectomy for endometrial cancer (Lap, n = 202; RALS, n = 99; 2018–2025). The primary outcome was CRP rise (POD1 minus the preoperative CRP level). Propensity score matching using preoperative covariates only (1:2, caliper 0.15 SD), multivariable regression, a formal mediation analysis with operative time as the mediator, and a test of the interaction between body mass index (BMI) category and surgical approach were performed. Results: RALS was associated with a greater CRP rise (2.88 vs. 2.13 mg/dL; p = 0.001) and a longer operative time (271.0 vs. 210.5 min; p < 0.001). In the matched cohort the median CRP rise was 2.91 mg/dL after RALS and 2.22 mg/dL after Lap, and the association persisted in a weighted model that accounted for the matched sets (β = 0.131; p = 0.023). On multivariable analysis, operative time (β = 0.0026 per minute; p < 0.001) and BMI (β = 0.0090 per kg/m2; p = 0.033) were associated with the CRP rise, whereas the surgical approach was not (β = −0.029; p = 0.623). Mediation analysis showed an indirect effect through operative time of +0.192 (95% CI, 0.120 to 0.278). The interaction between BMI category and surgical approach was not statistically significant (p = 0.750). Conclusions: The greater POD1 CRP rise after RALS was attenuated after accounting for operative time, and the mediation analysis was consistent with an indirect pathway through operative duration. This pathway cannot be established causally, because operative time could not be separated from surgeon experience, the learning curve and the era of each platform. A difference of this magnitude has no established clinical correlate, and no BMI-specific effect was demonstrated. Whether improving operative efficiency reduces the early postoperative inflammatory response should be evaluated prospectively.