ESR1 and breast cancer: Finally, a total of 7 miRNAs, containing hsa-let-7a-5p, hsa-let-7c-5p, hsa-miR-30a-5p, hsa-miR-29c-3p, hsa-miR-10b-5p, hsa-miR-195-5p, and hsa-miR-497-5p, were found to be favorable prognostic biomarkers for patients with ERα positive breast cancer in both TCGA and METABRIC databases.