Several 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 (primary tumor versus metastatic disease). 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.
159 patients with breast cancer and LNM who underwent surgery (either SLNB or ALND) between 2008 and 2016 at the university hospital of Leipzig 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 for ER, PR and Her-2 were analysed cay-by-case comparing results from the primary tumor within the breast and axillary lymph nodes. Proliferative activity was determined by MIB-1 immunohistochemistry and according to well established guidelines, the tumors were grouped into the different intrinsic subtypes as luminal A and B, Her2-enriched and triple-negative by the different immunohistochemical staining results.
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 tumor and LNM were different in 35% of all cases (56/159 patients); gain of HER2 in 5/56, activation of HRs in 6/56, loss of HER2 in 19/56 and loss of HRs in 37/59 cases.
Our results imply the high frequency of subtype differences between primary tumor and LNM. Subtype changes should be taken into account for an optimal and individual treatment. Larger studies are necessary to validate these data and gain further information.
B. Aktas.
Has not received any funding.
All authors have declared no conflicts of interest.