Comparative analysis of phenotypic features in the primary tumor, tumour buds and metastatic lymph nodes within Luminal A and Luminal B molecular subtypes of invasive ductal carcinoma of the breast

The study included 55 cases of formalin-fixed and paraffin-embedded (FFPE) tissues of breast invasive ductal carcinoma. The following algorithm has been made for further discussion by using immunohistochemical examination: antibodies against hormonal receptors; HER2; E-cadherin, Vimentin, Beta-catenin; Ki-67; Tumour buds were evaluated by using H&E stained slides and computer software Qupath (version 0.3.2). The results of the study show that estrogen expression is different in primary tumour mass and in tumour buds and its expression is diminished in the Luminal B molecular subtype respectively. Vimentin and Beta-catenin expression is showing similar changes, the quantity is much higher in tumour microclusters compared to the primary tumour and metastatic lymph nodes. It can demonstrate features of epithelial-mesenchymal transformation. Modifications in dynamics of proliferative activity are showing the lowest proliferative activity in tumour microclusters which can be discussed as the indirect manifestation of epithelial-mesenchymal transformation.