ERBB2 and breast carcinoma: Precision oncology relies on strategies such as genomic profiling to personalise care for breast cancer patients; the 21-gene expression assay (OncotypeDX Recurrence Score©, Genomic Health Inc., Redwood City, CA, USA) is routinely used in ER+/HER2-node-negative early breast cancer patients to select those who will derive the most benefit from systemic chemotherapy prescription, with first results from trial data supporting the expansion of indications to include those with 1–3 positive axillary nodes [6].