ESR1 and cancer: A higher rate of ERBB2-low disease was seen in hormone receptor–positive cancers (TNBC, 51.5% for ERBB2-low compared with 58.6% for ER-negative, PR-positive cancers; 66.1% for ER-positive, PR-negative cancers; and 69.1% for ER-positive, PR-positive cancers).