Comparison of Core Biopsy and Excision Materials in Terms of Histological Type, Histological Grade, Hormone Receptors, and Human Epidermal Growth Factor Receptor 2 Expression in Invasive Breast Carcinomas

OBJECTIVE Pre-operative diagnosis using core biopsy (CB) is one of the goals of the current approach for breast cancer, to learn the biological behavior of the tumor and reduce the costs by appropriate treatment planning. METHODS The histologic type, grade, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status of 201 patients were recorded for both the CB and excision specimens and compared with each other. RESULTS When we compared both materials, we found 89% concordance for histologic type and 75% for grade. There was a strong concordance for ER, PR, and HER2 status (96%, 89%, and 96%, respectively). CONCLUSION Higher rates of ER, PR, and HER2 positivity in core biopsies may be related to easier fixation, shorter unfixed time, or taking the CB from the tumor periphery. The CB is a reliable tool for pre-operative diagnosis and management of the breast cancer treatment. However, because of the CB may not represent the entire tumor, final decision for histologic type and grade should be made on excision specimens. Although it is low, the discordance rates in terms of hormone receptor (HR) and HER2 expression between two materials should be considered. If there is a discordance between histological type/grade and HR/HER2 status, especially in HR and HER2 negative cases, these studies should be repeated in the excision material. Internal and external controls should be used during immunohistochemical study, attention should be paid during fixation.