ERBB2 and breast carcinoma: However, most other studies have not found survival differences based on ERBB2-low status, highlighting that any prognostic association of ERBB2-low status is likely subtle.5,11,27,28,29,30 Undoubtedly, the introduction of antibody-drug conjugates will define the prognostic implications of ERBB2-low breast cancer moving forward given the marginal nature of these survival differences.