Concordance between HER-2 and steroid hormone receptor expression between primary breast cancer, sentinel node metastases, and isolated tumor cells

Our aim was to compare the HER-2 and hormone receptor status between primary tumor (PT) and sentinel node (SN) metastases in breast cancer.We analyzed 65 PTs with 42 macrometastases, 18 micrometastases, and 5 ITCs for the HER-2 amplification status and for the hormone receptor status.In HER-2-positive PTs, 26 of 29 metastases were HER-2-positive, including all six analyzed micrometastases and ITCs. Three macrometastases were HER-2-negative. In HER-2-negative PTs, 35 of 36 metastases were HER-2-negative. A low-grade HER-2 amplification was detected in one micrometastasis.A full concordance between the PT and SN metastases in both HER-2 amplification and ER and PR status was observed in 40 of 56 (71%) cases. These 40 fully concordant cases included 27 macrometastatic, 9 micrometastatic, and 4 ITC-cases.The concordance in HER-2, ER, and PR was high between the PT and their SN metastases. However, the concordance may be remarkably lower when analyzed simultaneously for all three predictive factors.