Neoplasias mamárias em cadelas : estudo epidemiológico e expressão de HER-2 em carcinomas

Abstract

Mammary tumors in female dogs are important diseases in veterinary medicine due to their high frequency, besides being a model for the study of breast cancer in women. So, it is necessary to continuous studies on the frequency of tumors and their clinicopathological characteristics. They also constitute a heterogeneous group of tumors in correlation with histological patterns and biological behavior, which makes it more complex and urgent to identify prognostic factors and to make it possible to diagnose and treat animals with mammary tumors more effectively. In the last years, there have been intensified the number of studies about the identification of molecular markers involved in the innumerable cellular events that occur during carcinogenesis, such as cell growth and differentiation, proliferation, invasion and metastasis. HER-2 is a membrane glycoprotein of the tyrosine kinase family, encoded by a gene with the same name, directly related to significant changes in cell proliferation and survival of tumor cells. During mutation process of this gene, hyperactivation of intracellular signaling cascade results in a rapid growth of tumor cells. In women, HER-2 overexpression is associated with breast neoplasms whose morphological parameters suggest poor prognosis and malignancy, resulting in a high rate of recurrence and mortality in the early stage of the disease, as well as a high incidence of metastases. However, in the female dog, until now the extensive variability of results obtained from immunohistochemical protocols proposed for molecular classification, keeps the meaning of HER-2 overexpression in these neoplasms obscure. In order to assist determination of the reliable prognostic factors for canine breast neoplasms, the present study: determined the prevalence of breast lesions diagnosed in female dogs in Laboratory of Veterinary Pathology of the Federal University of Uberlândia between 2004 and 2014, as well as the correlation between epidemiological aspects (age and breed) and clinicopathological (ulceration, tumor size and biological behavior) in the occurrence of breast tumors; verified the HER-2 expression in female mammary carcinomas of dogs and their relationship with the type and histological grade, age of patient, metastasis in lymph nodes or distants, tumor size and clinical staging.