Until recently, Sperdutos [7, 8] group has published a series of articles regarding diagnosis-specific prognostic factors including also molecular parameters for the markedly heterogenous population of patients with BM, e.g. HER2 and estrogen/progesterone receptor status in breast cancer [29], BRAF mutation in melanoma [32, 33] or EGFR and Alk status in NSCLC [30, 31]. The gene discussed is ERBB2; the disease is breast cancer.