Given that IFN can act as a double-edged sword, exerting both antitumor and protumor activities, and considering the high heterogeneity of ER+ breast cancer, which undergoes molecular and genetic alterations as the disease progresses [85], it is crucial to identify and characterize IFN signaling specific to each stage of the disease [86,87]. This evidence concerns the gene IFNA1 and breast cancer.