Objectives: Cervical cancer is one of the most common cancers in women worldwide. Although mortality has declined over the past 30 years in high-income areas, it remains a problem in several countries. Given that the prognosis of patients with recurrent or metastatic disease is poor, it is necessary to identify valuable predictive indicators to estimate survival outcomes in patients with cervical cancer.
Material and methods: We searched electronic databases such as PubMed, Web of Science, Embase, Ovid MEDLINE, and the Cochrane Central Register of Controlled Trials, and investigated the relationship between Programmed death-ligand 1(PD-L1) expression and prognosis. Chi squared tests and I2 were utilized to assess study heterogeneity, and publication bias was estimated using Begg's funnel plot and Egger linear regression test.
Results: Thirteen eligible studies with 1422 patients were included. Generally, high PD-L1 expression was conclusively associated with poor overall survival (OS) (HR: 1.31; 95% CI 1.03-1.66, p = 0.025). However, PD-L1 expression demonstrated no association with progression-free survival (HR: 0.93; 0.73-1.19, p = 0.57). High PD-L1 expression with a sample size over 100 indicated a shorter OS (HR: 1.51; 95% CI 1.13-2.01). High expression of PD-L1 in Asians represented a lower OS (HR: 1.52; 1.14-2.03). Overexpression of PD-L1 in tumor cells (HR: 1.57; 1.29-2.10) and tumor-infiltrating immune cells (HR: 1.75; 1.02-2.99) predicted poor OS. High PD-L1 expression (HR: 4.04; 2.58-6.31) showed a lower effect on OS with a cut-off value of 5%.
Conclusions: Our results indicate that high PD-L1 expression could be a valuable biomarker for predicting clinical outcomes in patients with cervical cancer.
Keywords: PD-L1; biomarkers; cervical cancer; diagnosis; immune cells.