Changes in Tumor-infiltrating Lymphocytes After Neoadjuvant Chemotherapy and Clinical Significance in Triple Negative Breast Cancer.

Abstract

Neoadjuvant chemotherapy (NAC) can affect tumors and the tumor microenvironment. As changes in tumor-infiltrating lymphocytes (TILs) after NAC and the resulting clinical significance have not been clearly defined, we evaluated both in triple negative breast cancer (TNBC). TIL level was histologically analyzed in pre-NAC biopsy and post-NAC operation specimens from 104 TNBC cases with residual invasive carcinoma after NAC. Forty-three cases (41.3%) showed decreases in TIL level, whereas 29 cases (27.9%) showed increases and no significant changes were found in 32 cases (30.8%). A decrease or increase in TIL levels corresponded to a better disease-free survival (DFS) as compared to unchanged levels. In multivariate analysis, a change in TIL level was an independent prognostic factor for DFS. We identified a prognostic significance of TIL changes after NAC. Assessment of TILs before and after NAC can provide valuable prognostic information for TNBC patients.