Introduction

Immunohistochemical evaluation of alpha estrogen and progesterone receptors, Her2neu and Ki67, has been the object of studies in women's mammary gland tumors, aiming to molecularly classify this neoplasia. In veterinary medicine, these markers have been the object of isolated studies in an attempt to relate them with morphological characteristics of tumors and their prognostic value.

Objectives

Classify canine mammary tumors in subtypes luminal A/B, HER2 or triple negative and correlate them with survival.

Methods

In a prospective study in the UNIMES Veterinary School Hospital, mammary gland tumors were collected after mastectomy, from 70 female canines. Clinical information, histopathology, TNM staging and survival were obtained from medical records. The material was subjected to immunohistochemistry with primary anti ER alpha, PR, and Ki67 Her2neu and submitted to HRP and DAB systems. For each marker, its own criteria of cutoff was established, in accordance with the literature. The statistical analysis was obtained, as applicable, by ANOVA, Chi-square Fisher's test, univariate analysis by Kaplan-Meier and/or multivariate analysis trough COX regression survival.

Results

We found association between ER alfa immunohistochemistry (IHC) and histological grade of tumors and between Ki67 IHC with grade and histological type of tumor. When these four markers were used for molecular classification of tumors, there was no association with survival. However, Ki67 showed a strong association with lymphatic invasion, pulmonary metastasis, and survival.

Conclusion

In this study, Ki67 demonstrated prognostic value relating to lymph node invasion, metastasis, and survival and therefore should be included in routine diagnosis of canine mammary tumors.