Abstract: Objective: To explore the association between systemic immune inflammation (SII) and recurrence-free survival (RFS) of adenoid cystic carcinoma (ACC) cancer, and to propose a reliable prognostic nomogram model. Methods: The preoperative SII was computed using clinical data from ACC patients who had radical resection at Zhengzhou University's First Affiliated Hospital between January 2013 and January 2020. The best cut-off value in the receiver operating characteristic curve (ROC) was used to compute SII for all patients, who were then divided into two groups: low SII and high SII. The Kaplan-Meier technique and the Cox proportional hazards regression model were employed by the Forest Plot to undertake survival analysis. On the basis of multivariate analysis, the nomogram was suggested. The C statistic (Area Under Curve, AUC) and Calibration Plots were used to assess the nomogram's consistency. Results: The research comprised a total of 119 patients. The average RFS duration was 49.34 months, while the median follow-up period was 45 months. ROC analysis determined the optimal SII cutoff value of 691.900. The high-SII cohort had significantly shorter RFS (χ²=19.487, Log-rank: P<0.001) than the low-SII cohort. The factors selected as predicting RFS were nerve invasion (HR=2.150, 95%CI: 1.027-4.500, P=0.042), and lymph node metastasis (HR=3.572, 95%CI: 1.705-7.480, P＜0.001) and high SII (HR=2.386, 95%CI: 1.048-5.480, P=0.038). C statistics was 0.732 (95%CI: 0.627-0.837). Conclusion: The lower the preoperative SII, the better the prognosis. The consistency of the nomogram revealed good predictive ability based on SII.

Key words: adenoid cystic carcinoma, systemic immune inflammation, nomogram, recurrence-free survival