ESR1 and triple-negative breast carcinoma: The subgroups defined by these markers are triple-negative breast cancer (TNBC, negative for all three markers), HER2-amplified disease further stratified by ER-status (ER-positive (ERpHER2p) and ER-negative (ERnHER2p)), and ER-positive HER2-negative tumors (ERpHER2n).