Long-term outcomes of surgical resection for thymic epithelial tumor with intrathoracic dissemination

OBJECTIVES The treatment of metastatic thymic epithelial tumors (TET) remains challenging with no established protocol, particularly regarding the feasibility of complete surgical resection. This study aimed to elucidate the long-term outcomes and identify risk factors influencing overall survival (OS) and progression-free survival (PFS) following surgical intervention. METHODS Between July 2000 and November 2021, 149 patients underwent surgery for metastatic TET with intrathoracic metastases at a single center. Of these patients, 121 met the inclusion criteria. Among them, 93 had thymoma including World Health Organization (WHO) types A, AB, and B1-B3, and 28 had thymic carcinoma. While 73 patients had pleural or pericardial seeding, 48 had lymph node or pulmonary metastasis. Synchronous metastasis was present in 72 patients, whereas 49 had metachronous metastasis. RESULTS The 5- and 10-year OS rates for the entire cohort were 76.4% and 55.1%, respectively. Multivariable analysis identified WHO type as a significant factor affecting OS (HR 4.260; 95% CI 2.139–8.482; p < 0.001). The 5- and 10-year PFS rates were 32.4% and 20.1%, respectively. In multivariable analysis, myasthenia gravis (MG) (HR 0.362; 95% CI 0.185–0.851; p = 0.018), WHO cell type (HR 3.071; 95% CI 1.857–5.079; p < 0.001), and number of metastases (HR 2.396; 95% CI 1.273–4.512; p = 0.007) emerged as risk factors for PFS. CONCLUSIONS Surgical resection for metastatic TET with intrathoracic dissemination demonstrated favourable OS; however, high progression rates necessitated repeated treatments. Factors including the number of metastases, WHO cell type, and the presence of MG were identified as significant determinants influencing PFS.