Original Article

Correlation between the Expression of PD-L1 and Clinicopathological Parameters in Triple Negative Breast Cancer Patients


  • Rabia Doğukan
  • Ramazan Uçak
  • Fatih Mert Doğukan
  • Canan Tanık
  • Bülent Çitgez
  • Fevziye Kabukcuoğlu

Received Date: 20.03.2019 Accepted Date: 10.07.2019 Eur J Breast Health 2019;15(4):235-241


Triple-negative breast cancer (TNBC) is a heterogenous group of tumors with no estrogen receptor (ER), progesterone receptor (PR) and Cerb-B2/HER2 expression. Programmed death ligand-1 (PD-L1) is a transmembrane protein located on both non-tumor and tumor cells and it has been shown to be associated with the escape of tumor cells from the immune system. PD-L1-targeted therapy alone or in combination is now an alternative strategy in several aggressive tumor types. In this respect, TNBC is a potential candidate having limited treatment options and poor outcome.

Material and Methods:

Sixty-one breast cancers with no expression of ER, PR and Cerb-B2/HER2 were chosen to study PD-L1 immunohistochemistry. PD-L1 staining and its correlation with main clinicopathological parameters were evaluated.


The percentage of PD-L1 positivity was 37.7% and 47.5% in tumor and tumor microenvironment, respectively. The positivity rate was higher in breast carcinomas with medullary features (83.3%) and metaplastic carcinoma (66.6%) subgroups. PD-L1 expression of tumors was positively correlated with their Ki-67 score and PD-L1 positivity of the tumor microenvironment. No significant relationship was found between the other variables.


PD-L1 expression rate was remarkable both in the tumor and the tumor microenvironment of TNBCs. Larger cohorts of TNBC are required to further describe their PD-L1 expression characteristics and help standardize PD-L1 immunohistochemistry assays in these tumors.

Keywords: PD-L1, breast cancer, triple-negative breast cancers, immunohistochemistry, monoclonal antibody