Overall, 3 of 6 (50%) metastatic TNBCs and 11 of 27 (41%) receptor‐positive tumours showed p63+ nuclei in a subpopulation of tumour cells, including 7 of 22 ER+ and/or PR+ tumours and 5 of 6 HER2+ cancers (including the ER+/HER2+ cancer). Here, ESR1 is linked to cancer.