ERBB2 and breast cancer: Despite the recently observed reduction in mortality due to early diagnosis and improvement of treatment strategies, BC continues to be the leading cause of neoplastic death in women, regardless of age, and long-term survival of metastatic breast cancer (MBC) patients remains 43–50 months for HER2 positive disease and 30–45 months for HER2 negative and HR positive subtypes [4, 5].