Prognostic and predictive value of tumor infiltrating lymphocytes in early breast cancer

It is well recognized that the immune system plays an essential role in tumor defense. The presence of tumor-infiltrating lymphocytes reflects an individual immunological response. In early breast cancer, the presence of TILs is associated with a more favorable outcome and response to therapy. In this review, we describe how TILs are assessed. Also, we discuss their role as prognostic and predictive biomarker in the neoadjuvant and adjuvant settings as well as in residual disease. Moreover, we discuss the possible implementation of TILs in daily clinical practice as well as in future clinical trials in order to fine tune prognosis and improve treatments.