Objectives The core needle biopsy (CNB) is an attractive alternative to surgical biopsy for the purpose of characterizing completely a malignant breast lesion for a tailored management. The purpose of this work is to study the concordance of the molecular profile of invasive breast cancer between the CNB and definitive pathology examination.

Methods We conducted a case-control study where each subject was her own control, including all patients with primary malignant tumors of the breast, collected prospectively, in our Department of Pathology and Cytology and treated at the Department of Gynecology and Obstetrics of the same hospital from January 1, 2015, to July 31, 2017. The studied molecular profile parameters were estrogen receptors (ER), progesterone receptors (PR), HER2 receptors (HER2), and Ki67.

Results We included 521 patients. The concordance between CNB and definitive postoperative specimen analysis with regard to the molecular profile parameters in invasive breast cancer was respectively of 100% and 96.3% for ER and PR, with an excellent agreement (respectively, k=1 and k= 0.905). The agreement in the diagnosis of tumors HER 2 overexpression was strong (k= 0.679). There was a difference between Ki 67 tumoral status (cut off at 20%) in CNB versus definitive postoperative specimen analysis in 53.1% of the cases with a weak agreement (k= 0.193). Consistency between CNB and postoperative specimen analysis in the distinction of luminal A tumors was 72.8%, 66.7% for luminal B, 90.1% for Her2 type and 86.4% for the basal type.

Conclusions CNB was reliable in determining the hormonal receptors’ status and the HER2 negative invasive breast cancer.