ERBB2 and breast cancer: In analyses of PAM50 intrinsic subtypes according to HER2 status (n = 1,576), luminal A subtype (58.9% vs. 51.8%) was more frequent and luminal B (33.4% vs. 34.9%) and basal-like subtypes (1.9% vs. 8.0%) were less frequent in HER2-low breast cancer compared with HER2-IHC 0 breast cancer among patients with HR-positive breast cancer.