Chemotherapy:Yes: 7487 (78.7)No: 2027 (21.3)Radiation therapy:Yes: 4489 (47.2)No: 5025 (52.8)Endocrine therapy:Yes: 5962 62.7)No: 3536 (37.2)Missing: 16 (0.1)Tamoxifen use among women with estrogen receptor–positive women cancer:Yes: 5178 (77.5)No: 1505 (22.5) The gene discussed is ESR1; the disease is cancer.