ERBB2 and breast cancer: The following approaches are therefore considered reasonable for these groups and are subject to ongoing trials: (1) for luminal A BC, de-escalating treatment by omitting RT for node-negative disease after lumpectomy for older women or after mastectomy with limited nodal involvement; (2) for hormone-positive/HER2+ BC, omitting RT for complete responders to neoadjuvant chemotherapy [56-59].