LAUSR

OBJECTIVE We aimed to compare the distribution of different molecular subtypes of invasive breast cancer (BC) between patients whose samples were obtained by core needle biopsy (CB) and surgical specimens (SS) and to assess the reliability of CB as a diagnostic method in this context. PATIENTS AND METHODS All patients (222) diagnosed with invasive BC were examined. Immunohistochemistry was performed on 40 samples obtained by CB and on 148 SS, while in 34 patients, the analysis was performed on both CB and SS. Molecular classification of BC was performed based on estrogen receptor (ER), progesterone receptor (PgR), Human epidermal growth factor receptor 2 (HER2), and Ki67 proliferative index status. RESULTS The most common molecular subtypes were Luminal A (43.2%) and Luminal B HER2- (29.7%). When comparing the frequencies of determined molecular subtypes, no difference was observed between samples obtained by CB and SS (p>0.05). Concordance analysis of molecular subtypes determined by immunohistochemistry on CB and SS was performed in 34 patients whose samples were obtained using both methods. No significant difference was observed in the designation of molecular subtype in relation to the sampling method (p>0.05). Results of immunohistochemistry analysis on CB and SS demonstrated good statistical agreement (Concordance rate=85.29%, Kappa=0.771, p<0.001). CONCLUSIONS CB might be a reliable method for the determination of the molecular subtype of invasive BC.