In a population-based study from the “Surveillance, Epidemiology and End Results” (SEER) database, 614/7575 patients (8.1%) with de novo MBC were diagnosed with BM at MBC diagnosis (105 with isolated BM and 509 with other metastatic sites).31 In a prospective cohort study from the “National Comprehensive Cancer Network” (NCCN) including 3394 HER2+ patients, BM was present at the first recurrence in 20 and 13% of patients with a HER2+/HR− and a HER2+/RH+ tumours, respectively.32 The gene discussed is ERBB2; the disease is neoplasm.