Effects of preoperative CALLY index and intraoperative LCA preservation on postoperative complications and LARS following robot-assisted mid and low rectal cancer surgery: a retrospective study.

OBJECTIVE: To investigate the impact of the preoperative systemic inflammatory index CALLY (albumin × lymphocyte count / C-reactive protein) and intraoperative preservation of the LCAon postoperative complications and the occurrence of low anterior resection syndrome (LARS) following robot-assisted radical surgery for mid–low rectal cancer. Additionally, to develop a Logistic regression–based nomogram prediction model for postoperative LARS and evaluate its clinical utility. METHODS: In this retrospective study, a total of 118 patients who underwent robot-assisted total mesorectal excision (TME) for mid–low rectal cancer at Shanxi Bethune Hospital between January 2021 and December 2024 were included. LARS was defined as the primary outcome and assessed at 6 months postoperatively using a validated LARS scoring questionnaire. Minor to Major LARS (LARS score > 20) was defined as a binary outcome variable. Postoperative complications were considered secondary outcomes and were recorded within 30 days after surgery for descriptive analysis. Least absolute shrinkage and selection operator (LASSO) regression was applied to identify candidate predictors, which were subsequently incorporated into univariate and multivariate Logistic regression analyses to construct a predictive model and corresponding nomogram for LARS. Internal validation was performed using the Bootstrap resampling method, and model performance was evaluated in terms of discrimination, calibration, and clinical net benefit. RESULTS: Among the 118 patients, 32 (27.12%) developed postoperative complications. The overall complication rate was significantly lower in the LCA preservation group compared with the non-preservation group (7.4% vs. 43.8%; OR = 0.10, 95% CI: 0.03–0.31, P < 0.001). Moreover, the incidences of postoperative fever (3.7% vs. 18.8%; OR = 0.17, 95% CI: 0.04–0.83, P = 0.03) and intestinal obstruction (0% vs. 12.5%; OR = 0.06, 95% CI: 0.003–1.05, P = 0.02) were also lower in the LCA preservation group. Correlation analysis revealed that postoperative complications were strongly associated with alcohol consumption history, diabetes mellitus, LCA preservation, and the CALLY index. Further analysis demonstrated that CALLY was correlated with multiple types of postoperative complications. Regarding functional outcomes, 26 patients (22.03%) developed severe LARS. The LARS score was significantly lower in the LCA preservation group than in the non-preservation group (P < 0.05). Multivariate Logistic regression analysis identified LCA preservation (OR = 29.226, 95% CI: 6.296–102.966), preoperative CALLY index (OR = 0.102, 95% CI: 0.012–0.858), and history of diabetes mellitus (OR = 18.91, 95% CI: 2.498–143.127) as independent predictors of Minor to Major LARS. The nomogram model achieved an area under the curve (AUC) of 0.881, demonstrated good calibration, and showed favorable clinical net benefit in decision curve analysis. CONCLUSION: This study preliminarily suggests that preoperative CALLY levels and intraoperative preservation of the LCAmay be associated with postoperative complications and Minor to Major low anterior resection syndrome (LARS) in patients undergoing robot-assisted mid-to-low rectal cancer surgery. The postoperative LARS nomogram constructed based on logistic regression represents an exploratory predictive model and demonstrates a certain discriminative ability. However, as this study is a single-center retrospective analysis with a limited sample size, its robustness and clinical applicability require further validation in large-scale, multicenter prospective studies.