Prognosis-related novel immunostaining pattern for programmed cell death ligand 1 and prognostic value of tumour-infiltrating lymphocytes in triple-negative breast cancer.

Abstract

This study aims to determine theprognostic significance ofprogrammed cell death ligand 1 (PD-L1) expression and tumour-infiltrating lymphocytes (TILs) in triple- negative breast cancer (TNBC). PD-L1 expression and TIL percentage were determined in TNBCs that did not receive neoadjuvant therapy. Therelationship between PD-L1 expression and thepercentage ofTILs with survival was investigated. Thepresence ofintratumoural PD-L1-positive tumour-infiltrating immune cells (TIICs) in tumours with ≥ 1% PD-L1 expression was identified as anew PD-L1 evaluation parameter. Thepresence ofintratumoural PD-L1-positive TIICs as anew parameter in PD-L1-positive cases increased overall survival. Thepercentage ofTILs increased in both overall and distant metastasis-free survival (p = 0.040 and p = 0.006, respectively). As aresult, it was found that therisk ofdeath was increased 5.18-fold (p = 0.013) in patients without intratumoural PD-L1-positive TIICs. This risk ofdeath was calculated to be 5.40-fold higher in patients with TIL percentage ≤ 10% than in those with > 40% (p = 0.024), and therisk ofdistant metastasis was calculated to be 11.95 times higher. In our study, we discovered that thepercentage ofTILs made astatistically significant difference in TNBC survival. Thepresence ofintratumoural PD-L1-positive TIICs in PD-L1-positive cases significantly increased survival.