Tawfik O, et al. - Researchers correlated differential expression of the programmed cell death-1 and its ligand-1 (PD-L1) in breast cancer (BC) and its microenvironment by examining a cohort of patients with BC, paired locally metastatic disease to regional lymph nodes (LN), and non-paired distantly metastatic disease. Results revealed that PD-L1 expression was mainly correlated with CD68 cells. Higher grade, hormone receptor negativity and highly proliferative tumors were correlated with PD-L1 expression. For the development of new treatment strategies, correlation of PD-L1 expression in BC and its microenvironment could be useful.