研究目的：
This study is a multi-center, randomized, prospective phase II clinical trial aimed at exploring and evaluating the efficacy of dalpiciclib combined with AI in neoadjuvant treatment for ER strong positive（ER≥50%），HER2-negative, Ki-67≤20%,T1-3N1M0 postmenopausal breast cancer. The primary objectives are to demonstrate non-inferiority in efficacy compared to chemotherapy and to assess its superior safety profile.
