Avaliação do papel prognóstico de neutrófilos e linfócitos em neoplasias de arranjo sólido da glândula mamária canina

Abstract

The morphological and immunohistochemical study of canine mammary neoplasms referred to as solid carcinomas showed that they can be composed of epithelial and/or myoepithelial cells, characterizing different histological types. In female dogs, greater inflammation is associated with higher histological grade, metastasis, and lymphatic invasion. However, the immunophenotypic characteristics and the importance of inflammation in the progression of these histological types are still unknown. The aim of this study is to characterize the intensity of inflammation, mainly lymphocytes and neutrophils, and the immunophenotypes in neoplasms with a solid arrangement of the canine mammary gland, and to associate them with prognostic factors (lymph node metastasis, mitotic count, Ki-67 index, and tumor size), cyclooxygenase (Cox-2) expression, tumor necrosis, and overall and specific survival of the female dogs. Out of 120 cases of mammary neoplasms diagnosed as solid and basaloid carcinomas, 65 were selected and reclassified as carcinoma with a solid pattern, basaloid carcinoma (BC), solid papillary carcinoma, malignant adenomyoepithelioma (MAME), and malignant myoepithelioma (MME). Immunohistochemistry was performed to determine the immunophenotypes (luminal A, luminal B HER-2 negative and HER-2 positive, HER-2 overexpressed, and triple negative), identify the expression of the Ki-67 protein, Cox-2, and labeling of CD3+ and CD79+ lymphocytes. The grading of the peritumoral and intratumoral inflammatory infiltrate was performed on histological slides using a score (distribution x intensity) that established a grade from I to III. Subsequently, the count of tumor-infiltrating lymphocytes and neutrophils (TILs and TANs) was performed in 8 hotspot fields (600x), and the count of CD3+ and CD79+ lymphocytes in 8 hotspot fields (400x). From this, the median for each cell type, in histology and immunohistochemistry, was established as a cut-off point to dichotomize the neoplasms into high and low intensity inflammatory infiltrate. Most of the solid arrangement neoplasms presented luminal B HER-2 negative immunophenotype, but MME and MAME had a significantly higher occurrence of luminal A compared to the other histological types. The grading of peri and intratumoral inflammation had no statistical correlation with histological types, immunophenotypes, Ki-67 index, and tumor size. BCs had significantly low intensity of intratumoral TILs compared to other histological types, and luminal B HER-2 positive and negative neoplasms showed high intensity of intratumoral TCD3+ lymphocytes. The increase in peri and intratumoral inflammation grade, and high intensity of intratumoral BCD79+ lymphocytes were statistically associated with lymph node metastasis. Mitotic count was proportional to the intensity of intratumoral TILs and BCD79+ lymphocytes. The Ki-67 percentage was proportional to the intensity of peritumoral TILs, TCD3+ lymphocytes, and BCD79+ lymphocytes. Cox-2 expression was not associated with the grade of inflammation, TILs intensity, and their subtypes, and TANs. Although the grade of inflammation was not associated with the survival of the female dogs, high intensity of peritumoral TANs was associated with lower overall survival, and high intensity of intratumoral TILs and T CD3+ lymphocytes were associated with lower specific survival. Lymph node metastasis increases the risk of death from neoplasia in female dogs, being the only variable that remained as an independent factor for the risk of death in female dogs with solid arrangement neoplasms. It is concluded that there is a relationship between histological types and immunophenotypes, and luminal B immunophenotypes present higher intensity of intratumoral TCD3+ lymphocytes. Intratumoral infiltration, although associated with some prognostic factors and reduced survival time, is not an independent factor. One of the main factors influenced by inflammation is the presence of lymph node metastasis, which is considered an independent prognostic factor in this study.