Well known since decades as an adverse prognostic factor, the more recent insight that breast cancers expressing HER2/neu are more susceptible to anthracycline-based chemotherapy (Pritchard et al, 2006) as well as the introduction of the HER2/neu antibody trastuzumab into the adjuvant setting has had significant impact on the prognosis of this particular subgroup of breast cancer patients (Slamon et al, 2001). The gene discussed is ERBB2; the disease is breast cancer.