ESR1 and neoplasm: Claudin‐low prediction was applied independent of PAM50 centroid predictor, and all claudin‐low tumours in this sample set were initially typed as basal‐like; this is not surprising given the majority of claudin‐low samples are ER–/PR–/HER2– and the clinical subtype TNBC is thought to be primarily composed of basal‐like and claudin‐low subtypes.46, 47