CORRELATION BASED ON THE PROTEIN EXPRESSION PROFILE BETWEEN PRIMARY CANINE MAMMARY TUMOUR AND ITS LYMPH NODE METASTASIS

Introduction: This study was aimed to evaluate the relationship between the molecular phenotype of the primary mammary tumour and its related lymph node metastasis in the dog to develop prognostic-predictive models and targeted therapeutic options. Materials and Methods: Twenty mammary tumour samples and their lymph node metastases were selected and stained by immunohistochemistry using anti-Estrogen Receptor, -Progesterone Receptor, -Human Epidermal growth factor Receptor 2 (c-erbB-2), -cytokeratin 5/6, -cytokeratin 14,-cytokeratin 19 and –protein 63 antibodies. Results: Four phenotypes (Luminal A, Luminal B, c-erbB2 over-expressing, Basal-like) were diagnosed in primary tumours and five (Luminal A, Luminal B, c-erbB2 over-expressing, Basal-like, Normal-like) in the lymph node metastases. Phenotypic concordance was found in 13 of the 20 cases, and 7 cases showed discordance with lymph node phenotypic profile being different than in the primary tumour. Discussion and Conclusion: According to the present results, the phenotype of the primary tumour assumes a predictive-therapeutic role only in concordant cases, this meaning that there should be a simultaneous evaluation of both the primary tumour and its lymph node metastasis. The treatment plan based only on the primary tumour phenotype could produce therapeutic failures if the phenotype of lymph node metastasis was different from that of the primary tumour