ESR1 and cancer: Of these 23 patients, 12 (52.2%) had ER-negative, HER-2-low or negative cancer, 7 (30.4%) had ER-negative HER-2-positive cancer, 3 (13.0%) had ER-positive HER-2-positive cancer, and 1 (4%) had ER-positive HER-2-negative cancer (Table 2).