Abstract:
Breast cancer is the most common malignancy in females globally. Various factors are responsible for its development
which include both genetic and hormonal causes. An important discovery is the role of the PD-1/PD-L1 axis in the
development of cancers. The PD-1-/PD-L1 pathway plays a part in allowing tumour cells escape from the host’s immune
response and hence permits the proliferation of tumour cells. PD-L1 expression has been observed in various breast cancers
at distinct levels such as in tissues and in blood. Different methods have been utilized for its detection including
immunohistochemistry, RNA sequencing and ELISA, amongst others. The results have been conflicting regarding the
expression of PD-L1 and the prognosis of breast cancer based on parameters such as overall survival and disease free
survival. Different immunotherapies have also emerged as a new modality to treat breast cancer. This review intends to
explore the prognostic significance of PD-L1 expression in breast cancers.