The Reliability of Core-Needle Biopsy in Assessment of Hormone Receptor, HER2, and Ki-67 in Breast Carcinoma

Objective: The purpose of this study was to compare the estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) status and Ki-67 index by immunohistochemical (IHC) analysis in breast carcinoma to determine the level of concordance between core-needle biopsy (CNB) and surgical specimens. Summary of Background: Accurate preoperative diagnosis of a breast lesion has recently been considered essential to the treatment strategy to achieve optimal treatment without delay. However, the reliability of using CNB specimens for IHC assessment is in relatively small number of cases and differing results between previous studies. Methods: The patients included in this study were 255 patients with primary breast carcinoma who had CNB and subsequent surgical resection at the Hospital of Dokkyo Medical University between 2010 and 2016. We compare the ER, PgR, HER2 status, and Ki-67 index by IHC analysis in breast carcinoma between CNB and surgical specimens. Results: There was a concordance rate between the ER, PgR, HER2, and Ki-67 IHC assessment of CNB and surgical specimens in 99.0%, 92.1%, 86.3%, and 91.5%, respectively. We also found small numbers of discordant cases in the estimation for which a discrepancy in determination led to a change in treatment. Conclusions: Our results do not entirely invalidate the use of CNB for assessment if they are the only source of tumor tissue available, but suggest a more cautious approach in their interpretation when clinical decisions are being made.