[Hot issues after the release of the guideline for HER2 testing in breast cancer (2024 version)]

After the release of the guideline for HER2 testing in breast cancer (2024 version), in order to improve the implementation of the guidelines, the Chinese Breast Pathology Group conducted a nationwide survey, gathering feedback from pathologists across China. Based on this, we analyzed and summarized seven key issues commonly encountered in pathological practice. These issues include the heterogeneity of HER2 protein and gene expression, reporting of HER2-ultralow, testing and interpretation issues of HER2 low-level expression, the establishment of external controls for HER2 testing, the interpretation standards for rare staining patterns, and the role of new technologies in HER2-low expression testing. These findings reflect the effectiveness and challenges in the implementation of the guidelines and provide valuable insights for the further optimization of the HER2 testing guidelines in the future.