ERBB2 and cancer: Luminal B cancers were subclassified into luminal B (HER2–) and luminal B (HER2+)cancers according to HER2 status, then further subclassified into luminal B (HER2–) PR+ orluminal B (HER2+) PR+ cancers if PR was positive, and luminal B (HER2–) PR– or luminal B(HER2+) PR– cancers if PR was negative.