KRT5 and breast cancer: This subgroup of BC is extremely heterogeneous: Lehmann et al. distinguished seven TNBC subtypes displaying unique gene expression profiles, including the luminal androgen receptor (LAR) subtype.1 These tumours are ER-, CK5/6-, but express genes usually expressed in ER + luminal tumours such as the androgen receptor (AR) and FOXA1, are distinct of basal-like tumours and represent 8–12% of all BC.