Laokulrath N.Gudi M.Salahuddin S.A.Chong A.P.Y.Ding C.Iqbal J.Leow W.Q.Tan B.Y.Tse G.Rakha E.Tan P.H.Mahidol University2024-06-162024-06-162024-01-01Histopathology (2024)03090167https://repository.li.mahidol.ac.th/handle/123456789/98806Human epidermal growth factor receptor 2 (HER2)-enriched breast cancer benefits significantly from anti-HER2 targeted therapies. This highlights the critical need for precise HER2 immunohistochemistry (IHC) interpretation serving as a triage tool for selecting patients for anti-HER2 regimens. Recently, the emerging eligibility of patients with HER2-low breast cancers for a novel HER2-targeted antibody–drug conjugate (T-DXd) adds challenges to HER2 IHC scoring interpretation, notably in the 0–1+ range, which shows high interobserver and interlaboratory staining platform variability. In this review, we navigate evolving challenges and suggest practical recommendations for HER2 IHC interpretation.MedicineReviewSCOPUS10.1111/his.152132-s2.0-851954518111365255938845396