The utilization of targeted therapy for programmed death ligand 1 (PD‑L1) has emerged as a prominent focus in contemporary clinical trials, particularly in the context of immune checkpoint inhibitors. The prognostic significance of the expression of PD‑L1 in invasive mammary cancer remains a subject of discussion in clinical oncology, requiring further exploration, despite its recognition as a biomarker for responsiveness to anti‑PDL1 immunotherapy. The present study was conducted to investigate the immunohistological expression of PD‑L1 in women with triple‑negative breast cancer (TNBC), with a particular focus for searching for the associated clinical and pathological characteristics. The present retrospective study examined the immunohistochemical expression of PD‑L1 in 40 formalin‑fixed paraffin‑embedded blocks provided by core needle biopsies from women with TNBC. Data analysis was performed by comparing PDL1 expression with histological grade, the presence or the absence of calcification, the presence or the absence of necrosis and axillary lymph node status at presentation. The positivity of PD‑L1 expression was found in 24 (60%) of the total number of samples. The mean number of PD‑L1 positive samples was 37.8333±21.857. There was a non‑statistically significant association between PD‑L1 positivity, histological grade and the presence of tissue necrosis. A statistically significant association was found between PD‑L1 positivity and the presence of calcification and positive axillary lymph node status at presentation. On the whole, the present study demonstrates that PD‑L1 expression is present at a relatively high prevalence rate in TNBC; thus, it is rational to examine PD‑L1 expression in women with TNBC.
