The B7 family molecules in oral squamous cell carcinoma: a systematic review. Part I: B7-H1 (PD-L1) and B7-DC (PD-L2)

INTRODUCTION: Oral squamous cell carcinoma (OSCC) is the most common cancerous lesion in the oral cavity. During recent years, no significant reduction in the survival rate has been observed. AIM: To systematically review the literature and to summarise correlations between B7 family proteins and prognosis in OSCC. MATERIAL AND METHODS: A systematic review of the literature about B7-H1 (PD-L1) and B7-DC (PD-L2) was carried out, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Thirty-six articles published before 22 May 2020 were included in the systematic review. RESULTS: The biggest study group consisted of 305 patients and the smallest – 10 patients. PD-L1 proved to be a prognostic factor in patients with OSCC. Immunohistochemistry was the most commonly used diagnostic method. CONCLUSIONS: Any mutations in the gene encoding PD-L1 and quantitative or functional changes in the status of PD-L1 may be important in the prognosis of OSCC.