Extended Preoperative Immunotherapy Duration Reduces the Risk of Myasthenia Gravis Exacerbation for Patients with Thymoma: A Multicenter Retrospective Cohort Study

INTRODUCTION: Patients with thymoma-associated myasthenia gravis (TAMG) frequently have a higher risk for clinical deterioration. Previous studies primarily focused on postoperative myasthenic crisis (MC), leaving intermediate and long-term MG outcomes after thymectomy largely unexplored. This study aimed to identify predictors of postoperative acute exacerbation within 1 year after thymectomy and explore the potential benefits of preoperative immunotherapies. METHODS: This multicenter retrospective study enrolled 347 patients with TAMG from 1756 individuals between February 2008 and October 2024. The primary endpoint was defined as the occurrence of acute exacerbation within 1 year postoperatively. Statistical evaluation employed logistic regression, Cox proportional hazards models, receiver operating characteristic analysis, and Kaplan-Meier curves. RESULTS: Of the study cohort, 96 patients (27.7%) had postoperative acute exacerbation of MG within 1 year. Multivariate Cox regression analysis identified that preoperative Myasthenia Gravis Foundation of America (MGFA) III-V was an independent risk factor for postoperative acute exacerbation (hazard ratio, HR 3.913, P < 0.001); preoperative immunotherapy duration > 14 days was associated with a protective effect (HR 0.419, P < 0.001). Multivariate logistic regression analysis identified preoperative MGFA III-V (odds ratio, OR 0.392, P < 0.05), reduced rate of R0 resection (OR 0.440, P < 0.05), and postoperative acute exacerbation (OR 0.245, P < 0.001) as independent risk predictors for achieving minimal symptom expression (MSE) at 1 year postoperatively. CONCLUSION: A preoperative immunotherapy duration exceeding 14 days is crucial for improving postoperative outcomes for TAMG.