Long-term prognosis in patients with thymoma combined with myasthenia gravis: a propensity score-matching analysis

Abstract

Introduction: We aimed to assess the impact of myasthenia gravis (MG) on the long-term prognosis in patients with thymoma after surgery and identify related prognostic factors or predictors.

Methods: This retrospective observational study included 509 patients with thymoma (thymoma combined with MG [MG group] and thymoma alone [non-MG group]). Propensity score matching was performed to obtain comparable subsets of 96 patients in each group. A comparative analysis was conducted on various parameters.

Results: Before matching, the 10-year survival and recurrence-free survival rates in both groups were 93.8 and 98.4%, and 85.9 and 93.4%, respectively, with no statistically significant difference observed in the survival curves between the groups (p > 0.05). After propensity score matching, 96 matched pairs of patients from both groups were created. The 10-year survival and recurrence-free survival rates in these matched pairs were 96.9 and 97.7%, and 86.9 and 91.1%, respectively, with no statistical significance in the survival curves between the groups (p > 0.05). Univariate analysis of patients with thymoma postoperatively revealed that the World Health Organization histopathological classification, Masaoka-Koga stage, Tumor Node Metastasis stage, resection status, and postoperative adjuvant therapy were potentially associated with tumor recurrence after thymoma surgery. Multivariate analysis demonstrated that the Masaoka-Koga stage and postoperative adjuvant therapy independently predicted the risk of recurrence in patients with thymoma after surgery.

Conclusion: There was no difference in prognosis in patients with thymoma with or without MG. The Masaoka-Koga stage has emerged as an independent prognostic factor affecting recurrence-free survival in patients with thymoma, while postoperative adjuvant therapy represents a poor prognostic factor.

Keywords: myasthenia gravis; prognosis; propensity score-matching; related factors; thymoma.

Figure 1

Flow diagram of the study.

Figure 2

Kaplan–Meier overall survival (OS) and recurrence-free survival (RFS) curves in patients in the myasthenia gravis (MG) and non-MG groups. (A) No significant difference in overall survival is observed between the MG and non-MG groups (p = 0.066). (B) No significant difference in RFS is observed between the MG and non-MG groups (p = 0.079). (C) No significant difference in overall survival is observed between the MG and non-MG groups (p = 0.801). (D) No significant difference in RFS is observed between the MG and non-MG groups (p = 0.425). (A,B) Before matching; (C,D) after matching.

Figure 3

Recurrence-free survival (RFS) curves associated with Masaoka staging and postoperative adjuvant therapy. (A) Statistically significant differences in RFS among Masaoka stages I, II, and III (p < 0.001). (B) Significant differences are observed in RFS with or without postoperative adjuvant therapy (p < 0.001).