ERBB2 and breast cancer: Interestingly, Miglietta et al. also describe an association between Luminal B-like subtype and HER2-low expression among breast cancer patients, while Schettini et al. found a possible correlation between HER2-low tumors and Luminal A subtype in a retrospective study (Miglietta et al. 2021; Schettini et al. 2021).