Reliability of Core Needle Biopsy in Evaluating Estrogen Receptor, Progesterone Receptor, and Human Epidermal Growth Factor Receptor 2, and Ki-67 Status

Abstract

Purpose: The preoperative determination of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), and Ki-67 expression status is crucial because these factors influence the therapeutic response to endocrine therapy, chemotherapy, and HER2-targeted therapy and help in the selection of adjuvant or neoadjuvant treatment. To evaluate the accuracy of core needle biopsy (CNB) in determining ER, PR, and HER2 status, and Ki-67 level status, we compared the results of CNB with those of surgical specimens. Methods: We retrospectively reviewed data from 191 patients with breast cancer whose ER, PR, and HER2 status, and Ki-67 level status was analyzed using both CNB and surgical specimens between 2013 and 2015. Patients who received neoadjuvant chemotherapy were excluded from this study. ER, PR, and Ki-67 were detected using immunohistochemistry (IHC) and reported as the percentage of positively stained cells. The cutoff point was 1% for ER and PR, and 14% for Ki-67. HER2 was determined by IHC and/or fluorescence in situ hybridization (FISH). HER2 positivity was defined as IHC 3+ or FISH (+). Results: In correlation analysis, Pearson correlation coefficients were 0.950 for ER expression, 0.813 for PR expression, 0.847 for HER2 grade, and 0.817 for Ki-67 expression level (p<0.0001). According to criteria for ER, PR, HER2, and Ki-67, the sensitivities of ER, PR, HER2, and Ki-67 assessment in CNB were 92.6%, 88.8%, 100%, and 80.6%, respectively. The specificities of ER, PR, HER2, and Ki-67 assessments in CNB were 90.7%, 86.0%, 99.1%, and 88.7%, respectively. Conclusion: The ER, PR, HER2, and Ki-67 status in CNB specimens correlated well with their status in surgical specimens. The HER2 status was the most accurately assessed factor in CNB specimens when compared to its assessment in surgical specimens. However, Ki-67 levels in CNB specimens were lower than those in surgical specimens.