The expression of programmed death-ligand 1 in patients with invasive breast cancer

The purpose of this study is to investigate the association between protein expression of programmed death-ligand 1 (PD-L1) and the clinicopathological features of patients with invasive breast cancer.

Clinicopathological data of 651 patients with invasive breast carcinoma were collected over a 1-year period. Patients whose breast tissue samples did not express genes for the estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor-2 (HER2) were classified as triple-negative breast cancer (TNBC). The correlations of PD-L1 expression with clinicopathological features and overall survival were determined using Pearson's correlation coefficient and logistic binary regression analysis, respectively.

Positive expression of PD-L1 was detected in 47% of patients with invasive breast carcinoma, compared with 69.3% of TNBC patients (P<0.05). Furthermore, expression of PD-L1 in patients with invasive breast carcinoma was significantly correlated with WHO grade, tumor size, vascular invasion, pathological stage, and the expression of ER, PR, nuclear associated antigen Ki67 (Ki67), p53 gene, cytokeratin 5/6 (CK5/6), and epidermal growth factor receptor (EGFR) (P<0.05). Logistic binary regression analysis showed that WHO grade, Ki67, p53, and EGFR were independent risk factors for the expression of PD-L1 in patients with invasive breast cancer. Moreover, PD-L1 expression in TNBC patients was significantly correlated with WHO grade, neuro-invasion, Ki67, CK5/6, and EGFR (P<0.05), but it was not correlated with age, tumor size, vascular invasion, number of lymph nodes, pathological stage, or the expression of ER, PR, p53, androgen receptor (AR), or vascular endothelial growth factor receptor (VEGFR) (P>0.05).

The high expression rate of PD-L1 in invasive breast cancer is closely related to some clinicopathological features. Thus, immunotherapy with PD-L1 inhibitors could be a potential treatment strategy for patients with invasive breast cancer.