This suggests that RS testing may be useful when performed on diagnostic biopsy in order to guide neoadjuvant therapies in ER+/HER2-breast cancer, with NET prescription a reasonable option to potentially downstage ER + cancers while providing data in relation to the in-vivo sensitivity of the tumour to endocrine agents for use in the adjuvant setting. This evidence concerns the gene ERBB2 and neoplasm.