ESR1 and invasive ductal breast carcinoma: According to the subgroup of invasive ductal carcinoma, whether the age is over 40 years old or not, T stage, N stage, TNM stage, histological grade, lymphovascular invasion, estrogen receptor (ER), endocrine therapy, radiotherapy, bone metastasis, liver metastasis, and lung metastasis, there was no significant difference between the HER2‐low group and HER2‐zero group in DFS (p > 0.05) and OS (p > 0.05) (Figure 1).