Expression of programmed death ligand-1 and programmed death-1 in samples of invasive ductal carcinoma of the breast and its correlation with prognosis

The aim of the current study is to investigate programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) expressions and to analyze the relationship between the expression of PD-L1 and PD-1 proteins and the molecular type, clinicopathological factors, and prognosis of invasive ductal carcinoma. We enrolled 136 patients with invasive ductal carcinoma of the breast. The expression of PD-L1 in tumor cells and that of PD-1 on paratumor-infiltrating immune cells was detected by immunohistochemistry, and the data were analyzed using SPSS software. The positive expression rates of PD-L1 and PD-1 in triple-negative breast cancer (TNBC) were 47.8 and 43.5%, which were higher than those of other subtypes (P<0.05). The expression of PD-L1 in tumor cells was correlated with the expression of estrogen receptor, progesterone receptor, and Ki-67 (P<0.05). The expression of PD-1 in the tumor-infiltrating immune cells was correlated with the expression of estrogen receptor, progesterone receptor, and Ki-67 and the histological grade (P<0.05). The expression of PD-L1 in tumor cells was correlated with the expression of PD-1 in paratumor-infiltrating immune cells (P<0.001). The expression of PD-L1 in tumor cells was found to be an independent prognostic risk factor with the progression-free survival rate for breast invasive ductal carcinoma (P=0.003). These results indicate that PD-L1 and PD-1 were highly expressed in TNBC which suggests that patients with TNBC may benefit from targeted immune therapies to a greater degree than patients with other subtypes. PD-L1 expression is an independent risk factor for breast invasive ductal carcinoma and expression of PD-L1 is expected to be a prognostic factor for breast cancer.