Prognostic and clinicopathological roles of programmed death‐ligand 1 (PD‐L1) expression in thymic epithelial tumors: A meta‐analysis

Abstract

Background Programmed death‐ligand 1 (PD‐L1) is one of the immune checkpoint proteins, and plays an important role in the progression and microenvironment of cancer. PD‐L1 expression has been associated with poor survival in many cancers. Several studies have also shown an association between PD‐L1 expression and the prognosis of patients with thymic epithelial tumors (TETs). In this study, we systematically evaluated the prognostic and clinicopathological roles of PD‐L1 expression in TETs. Methods We searched the literature through PubMed, Embase and Cochrane library and chose the eligible studies, and subsequently performed a meta‐analysis to evaluate the prognostic and clinicopathological roles of PD‐L1 expression in TETs. Results Six of the 75 articles found in the literature were selected. PD‐L1 expression was significantly related to unfavorable overall survival (hazard ratio 1.52, 95% confidence interval [CI]: 1.01–2.30, P = 0.046) in TETs. PD‐L1 expression was significantly associated with male gender (odds ratio [OR] 1.55, 95% CI: 1.08–2.22, P = 0.017) and higher Masaoka stage (OR 3.93, 95% CI: 2.44–6.32, P < 0.001). Conclusions PD‐L1 expression was correlated with unfavorable prognosis in TETs, indicating PD‐L1 expression could help determine the prognosis of TET patients.

Clinical Significance of Tumor Markers for Advanced Thymic Carcinoma: A Retrospective Analysis from the NEJ023 Study

“…To date, many studies on the clinicopathological prognostic factors of ATC have been conducted [ 5 , 18 , 23 ]. Recently, the prognostic factors of molecular characterization, such as insulin-like growth factor-1 receptor gene amplification [ 39 ], mesothelin [ 40 ], cyclin-dependent kinases [ 41 ], programmed death ligand 1 [ 42 , 43 , 44 ], epidermal growth factor receptor [ 39 , 45 ], c-KIT [ 45 , 46 ], and exportin 1 [ 47 ], have been investigated. Various results regarding these factors were obtained in each study.…”