Comparison of HER2, estrogen and progesterone receptor expression profiles of primary tumor and synchronous axillary lymph node metastases in 159 patients – indicating tumoral heterogeneity

Background:

Studies have shown that there may be change in the expression of steroid hormone receptors (ER and PR) as well as Her-2 as possible therapeutic relevant targets during disease progression. However, it is rarely considered into primary therapy that there can be already differences between the primary tumor and synchronous lymph node metastases (LMN). The aim of the present study was to compare the HER2/ER/PR expression profiles of primary tumors and synchronous LNM.

Methods:

159 patients with breast cancer and LNM who underwent surgery between 2008 and 2016 were included in this study. Formalin-fixed and paraffin-embedded (FFPE-material) were routinely examined immunohistochemically according to the ASCO/CAP guidelines using Ventana-platform. The results were analysed case-by-case. Proliferative activity was determined by MIB-1 immunohistochemistry and according to well established guidelines, the tumors were grouped into different intrinsic subtypes as luminal A and B, Her2-enriched and triple-negative by the different immunohistochemical staining results.

Result:

The discordance rates between primary tumors and axillary LNM were 14% (22/159) for HER2, 10% (16/159) for ER and 23% (36/159) for PR. The subtypes between primary tumors and LNM were different in 35% of all cases (56/159 patients); gain of HER2 in 5/56, activation of HRs in 3/56, loss of HER2 in 19/56 and loss of HRs in 37/56 cases.