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.
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Confirmed postmenopausal females diagnosed with invasive breast cancer.
Clinical stage T1-3N1M0.
Pathological examination confirmed: Strong positive for ER, negative for HER2. HER2 negative: Immunohistochemistry (IHC) suggests HER2 (-, +) or (++) but in situ hybridization (ISH) indicates negative. Strong positive for ER: ER immunohistochemistry test shows 50% or more tumor cells positive.
Pregnant or lactating women, and women of childbearing age who have a positive pregnancy test at baseline and do not agree to use effective contraception during the study.
Patients with a known history of severe allergic reactions to any investigational drug components (NCI-CTCAE Grade > 3) or with any clearly documented drug allergy.
Patients with bilateral breast cancer or inflammatory breast cancer.
Patients with metastatic (stage IV) breast cancer at initial diagnosis.