To this end, we selected the gene set that defines early estrogen response, as previous research has established a substantial association between the degree of estrogen response (Oshi et al, 2020), estrogen reactivity (Takeshita et al, 2022), and percentage of ER+ cells (Morgan et al, 2011) with survival outcomes after adjuvant endocrine therapy in breast cancer. This evidence concerns the gene ESR1 and breast cancer.