ERBB2 and neoplasm: However, needle biopsy samples may not fully represent the entire tumor because of the relatively small number of tissue samples obtained and the tumor heterogeneity.[6] Moreover, genetic heterogeneity within individual tumors significantly contributes to drug resistance and treatment failure.[7] Additionally, the discrepancy rate between limited biopsy and surgical specimens ranges from 3.5% to 14%.[8] Therefore, it is crucial to develop an accurate and noninvasive method to assess HER2 positivity in patients with BC.