The B7 family molecules in oral squamous cell carcinoma: a systematic review. Part II: B7-1, B7-2, B7-H2, B7-H3, B7-H4, B7-H5 (VISTA), B7-H6 and B7-H7

Introduction: The most common malignant neoplasm of the oral cavity is squamous cell carcinoma. It accounts for over 95% of malignant lesions in this area and is characterised by rapid spread and distant metastases. Aim: To collect and review the data on B7 family proteins as prognostic factors in oral squamous cell carcinoma and to describe their role in aggressive disease progression. Material and methods: A systematic review of the literature about B7-1, B7-2, B7-H2, B7-H3, B7-H4, B7-H5 (VISTA), B7-H6 and B7-H7, was carried out, following the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) guidelines. 9 articles published before 22 May 2020 were included in the systematic review. Results: The biggest study group consisted of 201 patients and the smallest – 40 patients. B7-1, B7-H3, B7-H4, B7-H5, B7-H6 and B7-H7 protein expressions were prognostic factors. Overall survival was significantly associated with B7-H3, B7-H5, B7-H6 and B7-H7. Immunohistochemistry was the diagnostic method used in all the studies. Conclusions: The data presented indicate the complexity of cellular and molecular processes related to the formation, development and invasion of oral cancer. Mutations in genes encoding the B7 family and changes in the B7 protein pathway may affect the prognosis of survival in patients with oral squamous cell carcinoma.