Tumour-infiltrating lymphocytes (TILs) in breast cancer: A predictive or a prognostic marker?

Breast cancer has not been considered as an immunogenic solid cancer type; however, recent studies demonstrate evidence of significant prognostic information that can be derived from immune cell infiltration via tumour-infiltrating lymphocytes (TILs) in patient tumours. The presence of TILs has been associated with increased response rates to cytotoxic chemotherapy as well as targeted therapies, leading to improved disease-free and overall survival in certain breast cancer subtypes. Accordingly, experts have developed a standardized methodology for evaluating TILs within clinical specimens in histopathological practice. An overview of a newly established practical guideline for TIL evaluation in breast cancer is described in this paper. Furthermore, this review discusses the predictive and prognostic significance of TILs, highlighting recent evidence linking TILs to prognosis in breast cancer. In addition, it summarizes the most current understanding of TIL composition as well as mechanisms of immunity generation and suppression. Overall, the current literature demonstrates that TILs are proving to be a promising target for the treatment of immunogenic breast cancers. © Springer Science+Business Media New York 2015.