In breast cancer, meta-analyses and large studies generally link higher ERβ/ERβ1 expression—particularly nuclear ERβ1—with better disease-free (DF), and OS, including among tamoxifen- or chemotherapy-treated groups; however, results differ depending on the isoform, analytical platform, and antibody specificity, and some reports show no association, highlighting the variability in assays and biology [25,26,27,28,29]. The gene discussed is ESR2; the disease is breast cancer.