Prognostic significance of EGFR, MUC1 and PD-L1 expressions in cases with triple negative breast cancer.

Purpose: Twenty percent of the breast cancers are triple negative (TNBC). Despite the impressive progression in the biology of this subgroup, data is limited as compared to hormone and/or HER2 positive cases. Thus, the aim of this study was to detect the expression levels and to identify the prognostic values of MUC1, EGFR and PD-L1 in TNBC.
Methods: MUC1, EGFR and PD-L1 expressions were detected by immunohistochemistry in 97 cases with TNBC. Associations between clinical and histopathological parameters with overall survival (OS) and progression-free survival (PFS) were analyzed using the Kaplan-Meier method and compared by the log-rank test. Prognostic effects were analyzed by Cox proportional hazard models.
Results: During a median follow-up of 93 months (0.6-168.7) the mean PFS was 110.1 and OS was 121.8 months. Tumor diameter (T), involved lymph node status (N) and TNM were found to be prognostic for PFS and OS. PD-L1 in microenvironment (PD-L1 ME) and EGFR expression were found to be associated with longer PFS and OS, but MUC1 and tumor PD-L1 (PD-L1 TM) expressions were not. All combined analyses showed that in the subgroups of MUC1, PD-L1 TM or ME positive, EGFR expression was correlated with longer PFS and OS than those who were not. Older age (≥70 years), T and N status and also EGFR expression were found to be independent prognostic factors for OS in Cox regression analysis.
Conclusion: EGFR expression was found to be one of the most important prognostic factors in addition to T and N status in cases with TNBC.