According to the 2023 European Society for Medical Oncology (ESMO) expert consensus statements (7), HER2-low expression is defined as an immunohistochemistry (IHC) score of 1+ or 2+/in situ hybridization (ISH) not amplified, accounting for 45%-55% of all breast cancer types (8). Here, ERBB2 is linked to breast carcinoma.