[Correlation analysis of PD-L1 expression and prognosis in triple-negative breast cancers]

Objective: To investigate the relationship between PD-L1 expression and the clinicopathologic features and prognosis in triple-negative breast carcinomas (TNBC). Methods: All 142 cases of TNBC were collected from the First Affiliated Hospital of Nanjing Medical University from February 2011 to December 2014, and the surgical excision or biopsy specimens from patients without chemotherapy and radiotherapy were included. Histopathologic analysis of stromal tumor infiltrating lymphocyte (sTIL) was performed on HE sections, and PD-L1 immunohistochemical staining was done with MaxVision. Results: The PD-L1 expression rate was 34.5% (49/142) in tumor cells, and was 62.0% (88/142) in sTIL. The PD-L1 expression in tumor cells was positively correlated with tumor size (r=0.181, P=0.031), Ki-67 index (r=0.211, P=0.012), sTIL (r=0.380, P<0.01) and PD-L1 expression in sTIL (r=0.447, P<0.01). The PD-L1 expression in sTIL was positively correlated with tumor grade (r=0.215, P=0.01), Ki-67 index (r=0.253, P=0.002) and sTIL (r=0.370, P<0.01). The high stromal CD8(+) /FOXP3(+) ratio was significantly associated with improved overall survival (χ(2)=4.186, P=0.041). The high percentage of sTIL was significantly associated with improved overall survival (χ(2)=12.427, P<0.01) and progression-free survival (χ(2)=4.057, P=0.044). Conclusions: In TNBC, PD-L1 expression is positively correlated with Ki-67 and sTIL; the stromal CD8(+) /FOXP3(+) ratio and sTIL are significantly associated with prognosis. The PD-L1 expression, stromal CD8(+) /FOXP3(+) ratio and sTIL are biologically important in TNBC, and all these correlative factors are important potential parameters in assessing immunotherapy for TNBC.