Prognostic implications of stromal tumor-infiltrating lymphocytes and programmed death ligand 1 expression in HER2-positive invasive breast cancer

Background: Tumor infiltrating lymphocytes (TILs) are known to be an important prognostic factor of specific breast cancer subtypes. However, to date, PD-L1(SP142)expression and tumor-infiltrating lymphocytes (TILs) has been only minimally reported in HER2-positive breast cancer cases.Methods In this study, CD8,CD4 and PD-L1༈SP142༉ were performed on tissue microarrays (TMA) representing 156 pretreatment cases of HER2-positive invasive breast carcinoma, including 55 hormone receptor (HR)-negative BC patients diagnosed from January 2010 to September 2015.Clinical data were collected, all cases were with complete follow-up data (23 recurrence and 2 deaths). The concordance rate in the tumor immune microenvironment(TIME) classification based on the PD-L1༈SP142༉expression status and CD8/CD4 + TILs count was analyzed.Results PD-L1 expression was identified in 49 cases (31.4%) in immune cells. We found there was no association was found between PD-L1 expression and DFS, but TIME classification was associated with DFS.Conclusion CD4 + and CD8 + lymphocyte infiltration was related to DFS in HER2-positive breast cancer.