No statistically significant differences were observed in the FGA of metastatic mixed mucinous, micropapillary, or metaplastic BCs compared to their primary counterparts, or to age-, menopausal status-, and ER/HER2 status-matched metastatic IDC-NSTs (Supplementary Fig. 4c, –e), potentially due to the small sample size of special types of BC other than ILCs analyzed in the study. This evidence concerns the gene ESR1 and breast cancer.