Standardized assessment of tumor-infiltrating lymphocytes in breast cancer: an evaluation of inter-observer agreement between pathologists.

Abstract

In breast cancer, there is a growing body of evidence that tumor-infiltrating lymphocytes (TILs) may have clinical utility and may be able to direct clinical decisions for subgroups of patients. Clinical utility is, however, not sufficient for warranting the implementation of a new biomarker in the routine practice, and evaluation of the analytical validity is needed, including testing the reproducibility of decentralized assessment of TILs. The aim of this study was to evaluate the inter-observer agreement of TILs assessment using a standardized method, as proposed by the International TILs Working Group 2014, applied to a cohort of breast cancers reflecting an average breast cancer population.