ERBB2 and breast cancer: Notably, other studies have shown an improved prognosis for BOM patients as compared with MBC patients with visceral or central nervous system (CNS) metastases.4,9–14 Our study showed a median OS similar to that previously reported by Niikura et al. and Ahn et al. with median OS of 4.9 years from distant disease diagnosis and 8.7 years from breast cancer diagnosis.15,16 We showed poorer OS in HR−/HER2− and HR−/HER2+ TS, similar to a smaller study of 226 BOM patients by Diessner et al. which showed improved OS in luminal A patients as compared with basal like or HER2 patients with BOM.17