Table 2. Clinicopathological features and prognostic significance associated with PD-L1 expression in thymic epithelial tumors.

Studies	Factors associated with high PD-L1 expression	Prognostic impact of high PD-L1 expression
Padda et al. (13)	Younger age, high stage, incomplete resection, aggressive histology	Worse OS (age- and sex-adjusted analysis)
Katsuya et al. (14)	Thymic carcinoma (rather than thymoma)	None
Yokoyama et al. (15)	Masaoka stage III/IV, WHO type B2/B3	Worse DFS
Yokoyama et al. (16)	None	Better OS
Marchevsky et al. (17)	Aggressive histology	–
Weissferdt et al. (18)	Neoadjuvant therapy in thymoma	None
Arbour et al. (19)	Thymoma (rather than thymic carcinoma)	Better OS

PD-L1, programmed death ligand 1; WHO, World Health Organization; OS, overall survival; DFS, disease-free survival.