Studying the Senescent T Cell Features and Its Relationship with the Chemotherapy Efficacy in Young TNBC

The goal of this observational study is to learn about the features of senescent T lymphocytes induced by chemotherapy and its relationship with the efficacy of neoadjuvant chemotherapy in young triple-negative breast cancer (TNBC) patients. The main questions it aims to answer are: * What are the senescent features of peripheral T lymphocytes in young TNBC patients receiving neoadjuvant chemotherapy and the relationship with the efficacy of neoadjuvant chemotherapy? * What is the relationship between senescent T cells and adverse events, DFS and tumor infiltrating lymphocytes? 1. Participants will receive 6 cycles of docetaxel + adriamycin/epirubicin + cyclophosphamide (TEC/TAC) neoadjuvant chemotherapy, and radical mastectomy after chemotherapy. 2.5ml peripheral venous blood will be collected before chemotherapy, after 2 cycles of chemotherapy, before surgery, and six months after surgery. 3.Clinicopathological data, chemotherapy-related adverse events and prognostic information of patients should be collected during the study.