ESR1 and cancer: BerEP4: Ber-Epithelium antigen 4; EMA: epithelial membrane antigen; CK: cytokeratin; p40: ΔNp63 isoform (squamous marker); CD56: neural cell adhesion molecule; CDX2: caudal-type homeobox 2; WT1: Wilms tumour protein 1; TTF-1: thyroid transcription factor-1; GATA3: GATA binding protein 3; ER: estrogen receptor; p63: tumour protein p63; Napsin A: aspartic protease napsin A; CUP: cancer of unknown primary; MDM: multidisciplinary meeting