CD3D and breast cancer: The possible reason is that higher immune scores indicated an enhanced immune system and function, which could be mobilized to increase the antitumor immunity of tumor microenvironments, so as to control and eliminate the tumor.5, 22 Furthermore, important genes, such as CD302, which were used to compute immune signatures, played critical roles in immune function.12 In addition, a study23 revealed that expression of T cell‐related marker, CD3D, was associated with higher pathologic complete response in patients with breast cancer who received neoadjuvant chemotherapy.