Garvin S, et al. - Because intrinsic subtype classification of breast cancer (BC) is based on the expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and proliferation marker Ki-67, researchers investigated macrophage features in cancer cells and intra-tumoral M2-macrophage infiltration (MI) relative to intrinsic subtypes in non-metastatic invasive BC treated with breast conserving surgery, with and without postoperative radiotherapy (RT). Among the intrinsic subtypes of pT1-T2 stage BC, significant differences in macrophage infiltration are noted. In luminal B HER2-negative tumors after RT, shorter recurrence-free survival was observed, implying that this phenotype might be more resistant to irradiation. ER tumor cell expression is inversely associated with infiltration of the macrophage. This investigation shows new perceptions into macrophage biological and clinical significance in BC.