In this study, the 70-gene prognosis signature (MammaPrint, Agendia Inc., Huntington Beach, CA, USA and Amsterdam, The Netherlands), which is validated as an independent prognostic indicator for node-negative and 1–3 node-positive disease, regardless of oestrogen receptor (ER) status (van ’t Veer et al, 2002; van de Vijver et al, 2002; Buyse et al, 2006; Bueno-de-Mesquita et al, 2008; Mook et al, 2008), was used to explore whether a subgroup of HER-2-positive breast cancer patients with a favourable long-term outcome could be distinguished. The gene discussed is ERBB2; the disease is breast cancer.