The basis for immunotherapy in cancer has revolved around the concept of immunogenicity. For a long time, breast cancer has been considered no immunogenic. However, the role of the immune system in the emergence of breast cancer has been firmly established. Random or inherited genetic and epigenetic abnormalities confer proliferative and/or survival advantages on certain cells. By targeting the new antigens created by these genetic changes, the immune system plays a central role in cancer control that can be host-protective or tumor promoting. Traditional pathology and immunohistochemistry, gene expression profiling, RNA sequencing, and combined scores have been used to assess the immunogenicity of breast cancer. Traditional pathology tools allow the assessment of breast cancer immunogenicity by studying the presence of Tumor-Infiltrating Lymphocytes (TILs) and assessing their types and correlation with survival and recurrence. While TILs were not found to have a prognostic value in the overall breast cancer population or ER-positive/human epidermal growth factor receptor 2-negative (ER+ /HER2-) patients, TILs were found to have a prognostic value for Disease-Free Survival (DFS) and Overall Survival (OS) in TNBC. In patients with TNBC who had residual disease after neo-adjuvant chemotherapy.