Concordance of HER2 Status between Core Needle Biopsy and Surgical Resected Specimens of Breast Cancer: A Narrative Review

Abstract

Background & Objective: HER2, a molecular biomarker, is routinely evaluated in breast cancer patients to guide therapeutic decisions. However, the concordance of HER2 status between core-needle biopsy (CNB) and surgical specimen (SS) samples is not always high, potentially affecting the accuracy of diagnosis and treatment. This study aims to review recent studies assessing the agreement of HER2 status between CNB and SS samples in breast cancer patients.
 Materials & Methods: A literature search was conducted in PubMed, Scopus, and Google Scholar databases from January 2018 to August 2023 using the keywords: concordance, core needle biopsy, resection, HER2 status. Ten articles meeting the inclusion criteria were selected for this review.
 Results: The results demonstrated variable concordance rates of HER2 status between CNB and SS samples, ranging from 83.3% to 99.5%. The primary factors influencing discordance were tumor heterogeneity, preoperative treatment, sampling error, and differing testing methods. Discordance was more prevalent in HER2-negative and HER2-low tumors compared to HER2-positive tumors.
 Conclusion: The concordance of HER2 status between CNB and SS samples is generally high but not perfect. Therefore, retesting HER2 status on SS samples is recommended to ensure optimal treatment decisions for breast cancer patients.