Risk factors of recurrence after surgical treatment for follicular thyroid carcinoma: Findings from a retrospective study at a tertiary medical center in China

This study aimed to investigate the risk factors for postoperative recurrence in patients with follicular thyroid carcinoma (FTC). A total of 207 FTC patients treated at our institution between January 2021 and December 2023 were retrospectively enrolled and stratified into recurrence (n = 27) and non-recurrence (n = 180) groups based on postoperative outcomes. Univariate analysis and binary logistic regression were employed to identify prognostic factors, while intervariable relationships were assessed using Pearson/Spearman correlation tests. Receiver operating characteristic curve analysis was used to evaluate the predictive efficacy of identified factors for FTC recurrence. No significant differences were observed between groups in age, sex, body mass index, extrathyroidal extension, T-stage, hemoglobin, albumin, total protein, or white blood cell count (P > .05). However, tumor size, M-stage, and systemic immune-inflammation index (SII) showed significant disparities (P < .05). Binary logistic regression identified SII and M-stage as independent risk factors for recurrence (P < .05). Receiver operating characteristic analysis demonstrated an area under the curve of 0.842 for SII (standard error: 0.039; 95% confidence interval: 0.765-0.919), with a Youden index of 0.51, yielding 66.67% sensitivity and 83.87% specificity. Using the optimal SII cutoff (148.32), patients were subdivided into SII ≤ 148.32 (n = 160) and SII > 148.32 (n = 47) cohorts, with the latter exhibiting significantly higher recurrence rates. Multivariate Cox proportional hazards regression confirmed SII as an independent predictor of poor prognosis (hazard ratio: 1.016; 95% confidence interval: 1.010-1.022; P < .001). Elevated SII is a clinically significant risk factor for FTC recurrence, warranting early intervention to mitigate recurrence risk.