Cancer Progression Is not Different in Mice of Different Gender Inoculated With Cells of the Triple-Negative 4T1 Breast Cancer Model

<bold>Background</bold>: Breast cancer in men is a rare and poorly studied disease, and its treatment is based on women breast cancer studies. However, clinical outcome is not the same in men and women. Basic studies and clinical trials in animal models provide detailed informa-tion on cancer, origin, development, cell signaling pathways, sites of metastasis, and target molecules. It is necessary to explore the biol-ogy of breast cancer in male animal models that allow observing their similarity.<bold>Methods</bold>: The triple-negative 4T1 breast cancer model was developed in both male and female mice and studied weekly during 4 weeks. For that, twenty 8-week-old female and male BALB/c mice were used. Sixteen mice (eight males and eight females) were inoculated into the second left thoracic mammary pad with 20,000 4T1 cells, resus-pended in 20 mu L phosphate-buffered saline (PBS). All samples were processed for immunodetection, characterized histopathologically and immunohistochemically.<bold>Results</bold>: In this work, we describe the development of a triple -neg-ative 4T1 breast cancer model in male BALB/c mice. Breast tumors