Abundant tumor infiltrating lymphocytes after primary systemic chemotherapy predicts poor prognosis in estrogen receptor-positive/HER2-negative breast cancers

Purpose The therapeutic effect of systemic treatment for breast cancer (BC) generally depends on its intrinsic subtypes. In addition, tumor infiltrating lymphocytes (TILs) are considered to be an independent factor for tumor shrinkage and disease prognosis. High TILs at baseline or after primary systemic chemotherapy are reported to be associated with better survival in triple-negative or human epithelial growth factor receptor 2 (HER2)-positive BCs. However, the prognostic value of TILs in estrogen receptor (ER)-positive and HER2-negative (ER+/HER2−) BC is still controversial.