Females >47 yearsScreen-detected breast cancer≤15 mm maximum tumour diameterNo mammographic microcalcificationUnifocal diseaseGrade 1ER strongly positive (Allred ≥7)PR strongly positive (Allred ≥7)HER2 negative (0 or 1+ on IHC, or 2+ and negative on ISH)Normal axillary ultrasound/equivocal axillary ultrasound with benign FNAC or core biopsyNo previous ipsilateral breast cancer or DCIS. The gene discussed is ERBB2; the disease is breast carcinoma.